(New) Master of Shrouds Handbook

[Akalsaris]

1. Introduction, Table of Contents, Overview of Master of Shrouds

Introduction:
The Master of Shrouds (MoS) is a divine caster prestige class from Libris Mortis intended primarily for neutral and evil clerics.  The prestige class trades a caster level at 1st level for the ability to summon incorporeal undead at certain levels in its progression. 

The undead are designed to be weak at the level you gain them, however the primary prerequisite for the class can be met by 3rd level through multi-classing into a second class with a good Will save.    If the prestige class is taken early in this way, the undead that you summon can be  powerful minions for your level.  At 5th level, for example, you'll be able to summon about 3-7 shadows a day for 3-7 rounds, and will be able to cast 2nd level spells - while a normal cleric will be able to cast 3rd level spells and rebuke any shadows the DM throws at him, but can't summon them.

Since your caster level will usually be 2 levels behind an average caster of your level, you will have to decide whether summoning powerful incorporeal undead (and the benefits of your single multi-class level) is worth that sacrifice.  In addition, the undead you summon are powerful at 5th level, but by 15th level and higher they are much less effective - so this is a prestige class that is best suited for mid-level games. 

Contents:
1. Introduction, Table of Contents, Other Links
2. Prestige class prerequisites and early entry
3. Rebuilding and retraining
4. Anatomy of the prestige class
5. Races
6. Base divine casting classes
7. Dip classes
8. Following up
9. Feats & Skill Tricks
10. Summons
11. Spells
12. Equipment
13. Party Role
14. Tactics
15. Final Thoughts
16. Sample Builds

Important abbreviations and slang used:
MoS: Master of Shrouds
ACF: Alternative Class Feature
UA: Unearthed Arcana
LA: Level Adjustment
DMM: Divine Metamagic
Dip: taking a single level in another class

Other Links:

Here is a link to an online preview of the Master of Shrouds, which gives most of the information you need for the class, so you don't have to "waste" money on Libris Mortis if you want to use this prestige class. 
http://www.wizards.com/default.asp?x=dnd/iw/20041015b

Credit must go to PhaedrusXY, who wrote the original Master of Shrouds handbook linked below, which led to my interest in the PrC.    That handbook is focused primarily on PhaedrusXY's experiences in a solo-play obstacle course designed to challenge optimized characters.
http://forums.gleemax.com/showthread.php?t=973248

Here is the build used by PhaedrusXY:
http://forums.gleemax.com/showpost.php?p=14767223&postcount=2604

Here's another MoS build I found in the competition:
http://forums.gleemax.com/showpost.php?p=14463800&postcount=601

Here is the necromancer's handbook by K, which has solid information on playing a character who's all about the undead, and also has a good section on the Master of Shrouds:
http://forums.gleemax.com/showthread.php?t=599129

Here's the Character Rebuilding guide by Nox_Noctis:
http://brilliantgameologists.com/boards/index.php?topic=141.0

Here's the Summoning Handbook for advice on summoning creatures.  A section appears at the end of this guide with some information specific to the MoS as well.
http://forums.gleemax.com/showthread.php?t=883099

Here's a pair of threads by Tiluvias on optimizing shadows:
http://forums.gleemax.com/wotc_archive/index.php/t-765789
http://forums.gleemax.com/wotc_archive/index.php/t-755481

[Akalsaris]

2. Early Entry

The prerequisites for the class are as follows:

Base Save Bonus: Will +5.  This is the big one we're going to concentrate on.  WoTC wants you to take this class at 6th level.  But by taking 2 levels in our primary divine caster class, and then dipping once in another class with a base +2 Will save, we're going to take the class at 4th level, when the summons from it are actually good.

Alignment: Any non-good.  So... you don't have to be evil.  In fact, you are probably going to want to play a neutral character in order to have the widest access to spells and possibly to spontaneously cast cure spells as a cleric.  Many DMs also frown upon evil characters, another reason that it's good to be neutral.  However, if you can get the "free" vile feats from Elder Evils (see the feats section), then being evil has some serious potential.

Skills: Concentration 5 ranks, Knowledge (religion) 5 ranks, Spellcraft 5 ranks. The skills mean that if you've got a base of 2 skills/level, you'll need at least a 10 int to enter early.  Otherwise, they're all common skills that you'd be taking anyways...no stupid weaving requirements here.

Feats: Augment Summoning, Spell Focus (conjuration).  The feats hurt this early in the game, and they're mostly useless for the next several levels too: and just when the monsters you can summon become worthwhile, your shadows are going to completely over-shadow them!  There are a few sneaky ways to get Augment Summoning that I know of: one is to use a variant of Conjurer from Unearthed Arcana for your 1-level dip, trading Scribe Scroll for Augment Summoning.  The other way I know is to take the Dragon Below domain from the EBCS, which grants Augment Summoning as a bonus feat - and the domain has a fairly solid list of spells as well.  However, it is campaign-specific and limited to a single cult.

Spells: Able to cast protection from good as a divine spell.  Note that using Arcane Disciple on a dread necromancer gives you protection from good as an arcane spell, and will not fulfill this requirement.  Taking Gatekeeper Initiate (EBCS) will give druids protection from good as a divine spell, however. 

Special: Able to rebuke undead. This requirement combined with the previous one means that you are probably going to either dip cleric or have it as the base divine caster class. 

[Akalsaris]

3. Rebuilding and retraining

Overview:
Character rebuilding is an option given in the PHB II that allows you to trade levels of one class or prestige class for another.  As I understand it, prestige classes can qualify for themselves with non-class abilities as long as you have one level in them already and keep at least 1 level of the base class.  So if a prestige class depends on a base save bonus, attack bonus, or ability to cast X level of spells, you can rebuild out of a base class - but not if you lose Rebuke Undead or another class feature (as I understand it).  For this reason, the full rebuilding option is only available for characters whose primary casting is cleric-based.  An archivist 2/cleric 1/MoS 2, however, could rebuild into an archivist 1/cleric 1/MoS 3.

You can trade up to 1/5th your level rounded up, meaning that if you do it at 6th, you can trade in a pair of "dead" levels (the 2nd level of your base class and the dip class) in for another 2 levels in MoS, making your summons very good at your level.  Since it takes a difficult mini-quest to rebuild character levels, you will probably want to wait until 6th and then trade in both levels.  Or start the character at 6th level and make it part of the backstory.

Now at 6th level, you've got the ability to summon wraiths with an automatic +2/+2 to hit and damage.  Wraiths are CR 5.  And you can summon between 3-7 of them in a single encounter...and still have room for your 3rd level spells with divine metamagic attached to them.
Even if it's legal by the books most sane DM's won't allow rebuilding.  But it's certainly something worth bringing up if you end up getting into the higher levels where your incorporeal summons are less effective and your character isn't holding his own against the other characters in the party. 

Retraining
Retraining is rebuilding's younger brother.  Each level you can trade 1 class feature, language, 4 ranks of skills, or 1 feat, possibly spending time and/or money to do so.  Unlike rebuilding, it's a lot more game and balance-friendly.  Here's an example of how it can benefit you:
Elf Cleric 1.  Feats: Point Blank Shot (Elf Domain), Precise Shot, Weapon Focus (Longbow) (War Domain).  At this level you're an archer, and probably more competent than the party ranger.
Cleric  2. 
Cleric 2/Sorcerer 1.  Trade Precise Shot for Spell Focus (Conjuration).  Now you're a crummy archer.  Make Augment Summoning your 3rd level feat. 
Cleric 2/Sorcerer 1/Master of Shrouds 1.  Trade the War domain for something useful towards your summoning, like the Charm domain. 
Cleric 2/Sorcerer 1/Master of Shrouds 2.  Trade the elf domain for something useful to your new role.

If you're human, you can also trade your racial feat for one that synergizes well with your 6th level feat, as long as you would have qualified for it at 1st level.  Taking Improved Initiative at 1st level, and then switching it to Quicken Spell at 6th and taking Divine Metamagic: Quicken Spell as your 6th level feat, for example.

In short, retraining makes the early levels of any class less painful - and since the early levels of MoS can be painful, that's a good thing for us.  It can also help at higher levels with spontaneous-casting dip classes such as the sorcerer, allowing you to retrain 2 spells/level a few levels later on when you don't need to cast Sleep or Color Spray anymore.   

[Akalsaris]

4. Anatomy of the Class

Stats:
Strength: this will probably be a dump stat.  If you want heavy armor or a composite longbow, however, you will need to sink some points into it. 
Dexterity: it's always good to have points in dexterity.  This is a tertiary stat though, especially with Zen archery.  MoS also get Hide as a class skill, which is based off of dexterity.
Constitution: you probably want points in here - this is 3.5, after all.  Secondary stat.
Intelligence: for some, it's a dump stat.  If you're an archivist, it's not, and cloistered clerics or players with dips in int-based classes will want some points here.  Remember that you'll need some skill points to qualify early, and plan accordingly.
Wisdom: generally a primary stat, you will generally want a 16 or higher here when possible.  Shugenja don't need this. 
Charisma: a primary stat, this enhances your undead summons/day, duration, and turn attempts.  You will want a 16 or higher here whenever possible.

Sample 32-point buy for a Cleric/Dread Necromancer-based MoS:
Str: 08
Dex: 12
Con: 14
Int: 10
Wis: 16
Cha: 16

HP: A d8, standard issue. 

Saves: A good Will save allows us to do the rebuilding trick mentioned above, but a low fortitude and reflex save hurts.  Dipping into a class with good saves in those categories can help, but I wouldn't make it a priority.

Skills: You have the standard cleric skills and also Hide.  Diplomacy is worth mentioning, since your charisma will often be decently high.  Your low skills/level and slight MAD means that you generally won't have too many free points though.

Abilities:

Caster levels: you lose a caster level.  It stinks, but what can you do?  Note that MoS only advances a divine spell-casting class, though an arcane variant would probably pass most DM's approval.
Extra Rebuking (Ex): Always useful, especially for Divine Metamagic and similar feats.  It also helps if you want to use Devotion feats from Complete Champion.
Rebuke Undead (Su): Again, this is useful, though situational.  Few PrCs advance rebuking, so think of it as something for free.  The description specifically states that it stacks with rebuking instead of doubling your pool.
Summon Undead (Sp): Your trademark ability.  This is where your true power comes from.  I'll go over each creature later, but for now it's good enough just to remember that incorporeal undead generally kick butt, and the higher your charisma goes, the more summons you get, and the longer they last. 
Improved Summoning (Ex): Good stuff.  Just keep in mind that this ability doesn't apply to Summon Monster or Summon Nature's Ally.  The Summon Undead chain stops when you will be 10th or 11th character level, and your last summons will become available when you are 13th character level, so this ability's usefulness begins to diminish around that time.  Note that this is an enhancement bonus, so it won't stack with some other spells.

[Akalsaris]

5. Races

Good LA +0 Races

Core:

Human: the golden standard.  With 2 feats required and 3 skills requiring 5 ranks by 3rd level, you're going to be strapped for feats and skills - this is often the ideal choice for a MoS.  If you're using flaws, the importance of this race diminishes slightly.

Halfling: in my opinion, this is the next strongest core option, with some save and skill boosts and small size to go along with the generally stealthy nature of a shadow-based caster. 

Non-core:

Strongheart halfling (FRCS): probably the best choice available in most games - gain the bonus feat of a human and nearly all the goodness of a halfling. 

Illumian (RoD): depending on your dip class, this can be a very solid choice, since the Illumian's sigils are often most effective when combining class abilities.  Just make sure that the combination of symbols you choose is stronger than the feat you're giving up by not being a human.

Kobold: with flaws allowed, venerable Dragonwrought kobolds from Races of the Dragon make excellent MoS characters just like any other caster, though it is difficult to enter early without flaws.  Jungle Kobolds from UA have adjustments of -4 Strength, +2 Dexterity, and -2 Intelligence, which go well with the MoS.  Of particular interest to kobolds with sorcerer dips is the following web enhancement to grant an additional "free" sorcerer level in return for a crummy feat:
http://www.wizards.com/default.asp?x=dnd/we/20060420a

Necropolitan (LM): a possible option since dumping Con reduces MAD, but I'm often wary of being rebuked or turned, and losing experience in order to become undead is counter to our purpose of gaining shadows as quickly as possible.  But if you're feeling cocky and you can start the game as a necropolitan without losing a level, go for it! 

Lesser Aasimar (FRCS): good resistances and +2 Wis/Cha.  i say go for it if it's available, and rock out with your tragic aasimar-turned-undead lover back story.

LA +1 Races

My opinion is that you should only take these races if your DM gives them out for free with no LA attached.  Even with LA buyoff these won't be worth it most of the time - "experience is a river" be damned, I say that you will want to be at the maximum level you can be to progress your summoning.

Aasimar: gives you Alter Self tricks and buffs Wis/Cha, your prime abilities. 

Chaos Gnome (RoS): this gives several nifty abilities and boosts your main stats nicely.

Feytouched:  Gives boosts to good abilities and some nice minor abilities.
http://www.wizards.com/default.asp?x=dnd/sp/20040213a

[Akalsaris]

6. Base Divine Classes

WoTC expects you to enter with a cleric.  With that said, it is generally the best-suited for the prestige class, and most of the attention of this guide will focus on cleric casting, feats, etc.  

Core:

Cleric: the golden standard for a MoS.  Since MoS stacks for Rebuke Undead, you can build your own army of undead eventually without even trying.  2 domains, full spell progression and heavy armor proficiency is just icing on the cake.  In core games, your feats will be limited - try to avoid item creation feats (you want to minimize experience costs) and metamagic feats (your spell-casting is already lower than normal).  You'll need a 1-level dip in any +2 Will save class.

Druid: a seriously weaker base class than cleric for the MoS.  First, you'd need to check if your DM allows you to be an undead-loving druid.  Druid summoners can be very strong at low levels, but with the caster level loss you won't be particularly good at it.  Another problem is that charisma is a dump stat for most druids, but necessary for the MoS.  You'll need a 1-level dip in cleric or in dread necromancer with the Gatekeeper Initiate feat.  

Non-Core:

Archivist (Heroes of Horror): You have a better spell selection than any other divine caster (if your DM is nice with scrolls!), and can do cool things with knowledge checks. The major downside is that you are dependent on lots of different ability scores.  You'll need a 1-level dip in cleric, dread necromancer, or cloistered cleric - cloistered cleric is by far the best choice to go along with archivist though.

Cloistered Cleric (UA): different enough to warrant its own entry, this variant from UA keeps the best abilities of clerics and trades their martial abilities for bard-style stuff such as lore and lots of skill points.  If Complete Champion is allowed, trading the Knowledge domain for the domain feat gives a small boost to attacks and damage at all levels.  Cloistered Cleric also gives you a wider list of spells known, including identify as a divine spell, removing the component cost of the spell (and for those of you who have DMs that waive the cost of identify: I envy you!)

In short, if you're trying to choose between cleric and cloistered cleric, and want a sneaky MoS, a loremaster MoS, or a diplomancer MoS, take this variant.  If you want a melee-based MoS, take the standard cleric (or cloistered cleric and dip into a class that gives good armor).  For any other kind of MoS, the two are roughly equal, though the Cloistered Cleric will let you get away with a lower intelligence for starting skills.  You'll need a 1-level dip in any +2 Will save class.

Divine Bard (UA): if you're absolutely dying for a bard MoS, you can do it.  You can't be good or lawful, and neutral divine bards can't cast spells with alignment descriptors, which means you will be Chaotic Evil, just like my last 2 bards.  Also remember that you're only getting 1/day Bardic Music and only the 1st level music abilities.  Divine Prankster from Races of Stone would be a good follow-up to MoS for gnomes.  You'll need a 1-level dip in cleric, dread necromancer, or cloistered cleric.  

Favored Soul (CD): Pass.  There's no good reason to take this over a cleric, since your Wis and Cha are equally important in both cases.  Because the Favored Soul has a sorcerer spell progression, you won't get 2nd level spells until 6th level.  You'd need a 1-level dip in cleric, dread necromancer, or cloistered cleric.

Spirit Shaman (CD): Since it's a class based on controlling and fighting spirits, its flavor is perfect for the MoS - and it gives you a way to gain druid spell-casting without the restrictions of actually being a druid.  It's not optimal, but it's different, and very flavorful.  You'll need a 1-level dip in cleric or cloistered cleric.

Shugenja (CD): Unlike every other caster on the list, the Shugenja is completely Wisdom-independent, so in a game where you rolled terribly or with a very low point buy this might be viable.  It still has mediocre spell progression like the sorcerer and a terribly limited spell list though.  I've tried playing a shugenja-based MoS and I enjoyed it, but I like optimizing terrible classes sometimes.  You'll need a 1-level dip in cleric or cloistered cleric.

[Akalsaris]

7. Dip classes

This is the longest section of the guide.  Since you have to dip in order to enter at 4th level, the class you choose can potentially have a big effect on your character (or simply filler to get you some needed saves or HP), and it's part of why I love this prestige class so much.  

Quick summary of classes:
Best HD: Knight (d12), Duskblade (d10), Hexblade (d10), Dragon Shaman (d10)
Best saves: Monk, Favored Soul (all good)
Best skills: Bard, Spellthief, Aristocrat, Archivist, Swordsage, Human Paragon, Beguiler (6/level)
Best attack bonus: Knight, Duskblade, Hexblade (+1)
Grants 1st level spell-casting: Druid, Cleric, Wizard, Warmage, Favored Soul, Healer, Sorcerer, Dread Necromancer, Beguiler, Shugenja, Archivist, Adept, Wu Jen

Core:

Bard: I think this is a mediocre dip, though I'm playing two bard dip MoS characters at the moment.  With only 1 bardic music/day and 0-level spells, this class mostly has nice saves, 6 ranks/level in a good skill list, charisma synergy, and the ability to use arcane items going for it.  The same goes for the divine/savage variants in UA, though the savage variant will help your fortitude save, while the divine variant will let you use your crummy bard spells in heavy armor.  Sadly, Inspire Courage won't even help your undead because it is mind-affecting.

Cleric: if you're not a primary cleric, you'll need this, dread necromancer, or cloistered cleric for the Rebuke Undead prerequisite.  It's a great class - I'd take a 1 level dip in cleric over a dread necromancer, though I'd take a cloistered cleric over a normal cleric.  

Druid: a decent core-only choice for a dip if your DM doesn't mind the whole "I love undead and nature" part.  If you can also trade your Wild Shape for the ACF on page 58 of UA for fast movement, favored enemy, track, and a monk's Wisdom to AC, you probably should, since you'll probably never get wild shape.

Monk: a so-so choice in my opinion.  You gain 4 skills/level, +2 Fort/Reflex/Will, and some bonus feats you'll probably never use.  If you can trade the bonus feats for useful ones, it might be good.  If you take monk as your first level, make sure to pick up the necessary ranks in concentration  and knowledge (religion), and some cross-class in spellcraft.

Sorcerer: If you're really tight on stats, you might need to take sorcerer just because you can't spare the points in Intelligence for wizard.  Also goes well with kobolds. 

Wizard: a great choice.  Gives a lot more versatility with arcane items and low-level spells, as well as a bonus feat.  In core-only, a conjurer or necromancer is probably your strongest choice for a dip.

Outside of core, a conjurer with the Unearthed Arcana ACFs will let you get Augment Summoning in place of Scribe Scroll, and also make your summon monster spells a standard action - some great bargains for 1 level!  The conjurer ACF from the PHB II is also very good for characters with a high intelligence, though you'd have to choose between it and the summoning one (I'd go for the teleporting one personally).

The necromancer variants from UA are also worth mentioning: one gives you a skeletal minion of questionable value in return for your familiar (it's based on your necromancer level, so it will be quite weak), and another gives 2HD and permanent enhancements to the strength and dexterity of undead you create in return for your bonus spell as a specialist - a great trade if you plan on creating a lot of undead.

Non-Core:

Please note that I have very little experience with psionic classes - feedback on those classes as dips is especially appreciated.

Classes that give +2 Will but are not covered in detail because they are generally mediocre as a dip for the MoS:
Gnome Paragon
Favored Soul
Truenamer
Shadowcaster
Shugenja
Spellthief
Healer
Hexblade
Warmage
Adept, Expert, Aristocrat

Archivist (HoH): a good dip, especially for the synergy with cloistered cleric.  Int-based casting and 6 skills/level.  

Artificer (EBCS): 4/level skills, +2 Will, trap-finding, scribe scroll, some minor benefits, Int-based infusions.  The personal weapon augmentation can certainly be useful though, as can the ability to scribe low-level scrolls from other classes' lists, and UMD is always a good skill to have.  Hard to go wrong with this class.

Beguiler (PHB II): a solid choice.  6/level skills from a great list, a limited but quite good spell list, trap-finding, and armored mage as abilities.  Int-based casting, however, which leads to some problems.  Knowledge (religion) isn't a class skill for beguilers, which could lead to problems with early qualification for MoS.

Binder: Another solid choice.  There are 5 vestiges you can bind with a single level, or 9 with practiced binder.  Bind Savnok for free full plate at 1st level, or Naberius for a diplomancy build. 

Church Inquisitor (CD): Originally suggested by Surreal or carnivore I believe, this is a prestige class you can enter as a cleric at 4th, gain +2 Will, and then enter MoS at 5th.  Is delaying access to the MoS by 1 level worth saving a level of spell progression?  Well, that depends.  If you're using rebuilding, then it certainly isn't.  Alignment restrictions are also tight here - you must be part of a LG church or religious order, though the deity doesn't specifically have to be LG, and you must be LN, which isn't so bad.  I wouldn't go this route with most characters, but it is an option.

Cloistered Cleric (UA): a dip for the non-cleric base casters such as spirit shamans, this is a fine choice - 6 skills/level, 3 domains, and a Bardic Lore ability all in one.  Two thumbs up.  

Dragonfire Adept (DM): An excellent dip, with 4 skills/level, good Fort and Will saves, plus a crummy breath weapon, a crummy bonus feat, and an invocation.    Entangling Exhalation is a fine feat from Races of the Dragon that will let you use your breath to entangle foes with no saving throw allowed, helping your buddies to beat on them some more and giving you something useful to do in between summoning incorporeal undead.  Your bonus feat also allows you to take Draconic Heritage, which can add some skills to your list for all classes, and gives some other small bonuses.
One interesting choice would be to take the Darkness invocation, allowing your wraiths and spectres to fight outside at all times.  Drow of the Underdark also has the feat Instinctive Darkness to make Darkness an immediate action to cast, allowing you to immediately begin summoning wraiths.    Suggested invocations: Darkness or Beguiling Influence.  Draconic Knowledge is another solid choice for characters with the Knowledge Devotion feat.

Dragon Shaman (PHB II): a mediocre choice.  A d10 HD but cleric attack progression?  Anyhow, you get some small, constant auras for the party - Vigor, Senses, and Toughness are the default choices.  

Dread Necromancer (HoH): one of the best dip classes.  The only dip that stacks with cleric for Rebuke Undead for players with DMs who frequently send the undead at them (and if your DM rules that they are separate pools, then its even better for DMM users!).  Also, Charnel Touch allows you to heal undead allies for unlimited amounts between battles, and gives a decent touch attack at very low levels, especially if it stacks with inflict spells.  If you're taking Dread Necro, consider the Tomb-Tainted Soul feat, which lets you heal from negative energy.  Solid spells from a small spell list.

Duskblade (PHB II): A strong choice.  Strong Fort and Will, +1 BAB, all martial weapons, armor, and most shields, armored mage, and spells from a limited list with Int-based casting.  This could help make a decent melee character.

Human Paragon (UA): surprisingly, this is a good option!  You can go Human Paragon 1/Cleric 1/Human Paragon +1 and net Adaptive Learning in a skill of your choice, as well as a bonus feat.  Makes it very easy to enter a skill-based PrC after MoS as well, and gives you more wiggle room for feats at low levels.  

Incarnate (MoI): from Magic of Incarnum, the incarnate could make a good dip if there are some soulmelds you really want - and there are at least a few worthwhile ones to pick from for any character.

Knight (PHB II): Interesting choice - gives +1 BAB, a d12 (!) HD, and a Charisma-based challenge, but you need to be lawful and follow a code that prevents you from gaining a bonus from flanking with your summons.  If you want to be the party tank, this could be worthwhile, especially if you take the Goad feat from Complete Adventurer.  It's also good if you are using the rebuilding trick, since the HD and BAB will help while you're still pretending to be an archer or something.    

Marshal (MH): A good dip.  MoS has Diplomacy as a class skill, so if you want you can go Cleric/Marshal/MoS for a respectable diplomancer build.  Or you can just give your allies a bonus on flanking damage and use hordes of shadows and summoned skeletons to make good times for everybody.  If you're willing to sacrifice another caster level, having a major aura will make you an even better buffer.

Spirit Shaman (CD): strong Fort and Will, 4 skill ranks, and choosing spells from the druid spell list without druidic restrictions about the undead make this a decent choice.  Also, the flavor fits the MoS perfectly.

Swordsage (ToB): a decent choice for a melee-focused MoS - gives +2 to Reflex and Will, 6 skill ranks/level, and opens up ToB fun.  Can definitely help viability at lower levels.  Suggested maneuvers/stances: Distracting Ember will help you and your summons, Sapphire Nightmare Blade works off of a skill you'll be maxing normally, Leading the Attack helps your summons against the foe you hit, Island of Blades stance lets you flank with adjacent summons.  The Shadow Hand school also fits the MoS flavor very well.  If you're willing to sacrifice another caster level, gaining wisdom to AC in light armor can be great for cloistered cleric entries.

Warlock (CA): a great choice for many of the same reasons as the Dragonfire Adept.  Suggested invocations: Darkness, Entropic Warding and Beguiling Influence are all excellent for the MoS.  The flavor fits well too.

Wu Jen (CA): as a 1-level dip, it's pretty hard to argue with an initiative reroll and a metamagic feat of your choice, especially if alternative class features for wizards are not an option for the campaign.  Not a terrible choice, and the Guardian Spirit feat from Complete Arcane gives 2/day initiative rerolls and a 1/day save reroll, which is quite solid for a single feat.  Limited spell list and int-based casting though.

[Akalsaris]

8. Following Up

After the MoS, you should still have 7 levels left.  Here's some PrC's that might be worth looking into, in the shortest part of this guide...

Contemplative (Complete Divine): good as a 1-level dip or for all 7 levels.

Eldritch Theurge (Complete Mage): For the warlock/clerics, you take another 1-level divine CL hit to get very solid advancement for your warlock side and some cool abilities.  

Divine Prankster (Races of Stone): Good for gnome bard/clerics or divine bards - nothing too exciting though.

9.  Feats & Skill Tricks

Feats: You will be strapped for feats for the early levels, and will probably want to get DMM spells for the mid-levels, and take feats to qualify for a PrC in the later levels.

General feats:  

Able Learner (RoD): a staple of many multi-class builds.  

Zen Archery (CW): helps reduce MAD by letting you drop your dexterity a few points while maintaining a decent attack bonus.  However, your BAB will be quite low for most of the game, so it's generally a filler feat.  Same with Point Blank Shot and Precise Shot.

Practiced Spellcaster (C. Arc.): gain back the 2 CL you lost, or increase your dip's CL by 4.  Or both.

Beckon the Frozen (Frostburn): putting that Spell Focus: Conjuration and Augment Summoning to good use, this gives your summoned undead an extra 1d6 cold damage per hit.  Check with your DM if it affects your incorporeal undead summons first though, as they are summoned through a spell-like ability.

Snowcasting (Frostburn): makes your spells cold-subtyped if you use a handful of snow, and add 1 to the spell's level if it's already cold-subtyped.  Good in an arctic campaign, especially since it lets you take Icy Calling, giving summoned creatures an enhancement bonus of +4 to Strength (useless to your shadows) and Dexterity, and possibly maximized hit points.  Lots of good spells in Frostburn (see further below) as well.

Corpse-crafting (LM): this is the first in a line of feats that improves the power of undead you create.  Be careful, since the chain is fairly feat-intensive.  The first feat in the chain is the best, and keep in mind that Deadly Chill only applies to corporal undead

Divine Metamagic and Devotion feats:
Two things to keep in mind: first, the errata for Complete Champion has clarified that you no longer permanently sacrifice turn undead attempts to power devotion feats.  Second, keep in mind that Extra Turning grants bonus turn attempts to each pool of turn attempts you have, such as turning granted by the elemental domains.  

Extra Turning: getting more turn attempts for DMM or whatever is almost always a safe bet for a feat when you've run out of ideas.

Knowledge Devotion (CC): good for archivists and cloistered clerics, gives attack and damage benefits depending on knowledge checks.  Can possibly be gotten by trading the Knowledge domain from cloistered cleric.

DMM: Quicken Spell: a decent choice, since you can always use your standard actions to summon shadows.

DMM: Persistent Spell: good, though best for high-level games.

DMM: Chain Spell: excellent for sharing buff spells among your summons and allies.

Air Devotion: very solid benefits against ranged attackers.

Animal Devotion: if you don't want to use divine metamagic, this is a versatile devotion feat with solid effects, and one of the easiest ways to gain flying.

Law Devotion: another solid feat, especially relevant for Church Inquisitors (who are basically restricted to Lawful Neutral).  

Water Devotion: gives you another summon that is useful mostly as a scout and at low to medium levels as a flanker and meat-shield.  I like it since it works off of your turn attempts/day at a 1:1 ratio, which can quickly result in a lot of water elementals.  
If your DM house-rules that summoning-enhancing feats such as Augment Summoning effect your elementals (since by RAW they do not), then consider the Augment Elementals feat from Magic of Eberron, which gives them +2 enhancement bonus to attack & damage, and grants temporary hit points equal to 2x their hit dice, which makes them much better mini-tanks.  I believe that Water Devotion and Augment Summoning are best as early feats to be retrained later on for divine metamagic or something similar.

Dip Class-Specific feats:

Draconic Heritage (Sorcerer/DFA: Races of the Dragon): Good as a method to gain a class skill and several minor benefits.

Initiate of Milil (Bard: Champions of Valor): stacks cleric and bard for the power of bardic music.  You'll still need Extra Music if you want to sing more times per day though, and your actual cleric level will still be low.

Entangling Exhalation (Dragonfire Adept: Races of the Dragon): gives constant crowd control options with your breath weapon at little cost.  Entangle is a great debuff to help your party and summons hit opponents for low-mid levels.

Tomb-tainted Soul (Dread Necromancer: Libris Mortis): allows Charnel Touch and other negative energy to heal yourself.  After all, touching yourself is a standard action.

Gatekeeper Initiate (Druid: EBCS): gives some benefits against aberrations, and protection from evil as a divine spell on the druid list (as well as some other nice spells, like imprisonment), which allows a druid-based MoS to take dread necromancer in place of cleric for the turn undead requirement.

Repel Aberration (Druid: EBCS): gives druids the ability to turn aberrations and requires the Gatekeeper Initiate feat, plus it benefits from the Extra Turning you get from MoS.  Not essential, but pretty cool in an aberration-heavy game.

Open Chakra, Least (Incarnate: MoI): allows you to use a Necrocarnum Crown to summon a zombie without taking 2 levels in Incarnate, for example.  Of course, then you're wasting a 6th level feat on a 1HD skeleton, so maybe you shouldn't take this after all.

Instinctive Darkness (Dragonfire Adept or Warlock: DoTU): makes the Darkness invocation an immediate cast spell.  

Blend into Shadows (Dragonfire Adept or Warlock: DoTU): gives Hide in Plain Sight within 10 feet of magical darkness.

Guardian Spirit (Wu Jen: Complete Arcane): gives 2/day initiative rerolls and a 1/day save reroll

Skill Focus (Diplomacy): Take at 1st level if you plan on dipping Marshal and want a different feat at the level you take Marshal, as the class description states that if you already have Skill Focus (Diplomacy) you may choose another feat instead.

Elder Evils vile feats: for the low price of swearing your soul to a Cthulhuesque horror, you can get free feats!  Here's some metagame thinking: if you can use Libris Mortis and/or Heroes of Horror, your DM is probably either  lenient with books or a horror fan.  And in either case, that means there's a good chance Elder Evils will get the go-ahead.  

In particular, Insane Defiance, Dark Speech, Dark Whispers, and Filthy Outburst all require high will saves, which you will get quite early.  Evil's Blessing benefits from a high Charisma, so it's a good 1st-level pick.

Skill Tricks:

Master of Stories: goes well with Cloistered Cleric and Archivists.

Shrouded Dance: requires perform and hide, so for the bard, monk or human paragon dips this can get you concealment as a move action and goes well with the shadow motiff, especially since hide is a class skill for you.  You can also get Perform as a class skill on a sorcerer or Dragonfire Adept through Draconic Heritage: Battle Dragon.

[Akalsaris]

10. Domains and Spells

Domains of note:
Knowledge: gained as a bonus domain through Cloistered Cleric and can be traded for Knowledge Devotion in Complete Champion.
Dragon Below (EBCS): grants Augment Summoning as a bonus feat and has a good spell list.
Charm Domain: boosting your charisma by 4 points seems like one of the best options to me.
Family: protect creatures equal to your charisma with a +4 dodge bonus to armor.  Meh.
Halfling: gain your charisma to rogue-type skills for a good duration.  Could be interesting on a stealthy character.
Mysticism: Great power, and great spell list too
Summoner: if using retraining as an option, this is a good low-level domain choice.  Good spell list too.
Trade: A free action detect thoughts for several minutes?  Nice!  Also gets you Eagle's Splendor.
Undeath: When in doubt, go DMM and grab the Undeath domain.
Planning: a staple of DMM builds, this grants Extend Spell and a great spell list.
Baator (must be lawful evil, only gain 1 domain): the ability to see perfectly in all darkness meshes well with a warlock or dragonfire adept dip.  It's bound to annoy your party members if they can't do the same though.  Solid spell list.

Afflux from Libris Mortis seems like one of the best deities to pick for the MoS if you can't pick your own domains - he grants the Deathbound, Evil, Knowledge, and Undeath domains.  

Spells:
You probably want to be on the look out for long duration buffs and swift-action spells to mesh with your standard-action summons.  Otherwise, buffs that you can cast on the whole party and your summons are always appreciated, as are all of the usual divine spellcaster goodies.

Frostburn adds a lot of solid spells for you, including:
Ice Slick (Cleric 1): Basically a version of Grease that creates a 20-ft surface of ice.  This allows you to use some of your other cold-based spells, and also screws opponents without affecting your flying incorporeal undead.
Algid Enhancement (Cleric 6): buffs cold-subtype creatures, including those you summon with Beckon the Frozen.
Blood Snow (Cleric/Druid 2): great aoe spell that deals Con damage and nauseates opponents (both non-effects for your summons) at a long range with a big radius.  Only problem is that you need to cast it on a snowy field.
Defile Snow and Ice (Cleric 3): grants undead +4 turn resistance, and cold-typed creatures SR 15 against fire effects.  Needs an area of snow or ice.

Other books:
Ghost Touch Weapon (Cleric 4, Libris Mortis): makes a weapon ghost touch, so your summons can wield weapons you give them.  
Incorporeal Enhancement (Sorc/Wiz 3, L. Mortis): gives AC, HP, and turn resistance, though the attack bonus won't stack with your 5th level ability - with a duration of 24 hours!  Great for archivists, especially if you have some undead permanently under your control.
Magic Fang (PHB): depending on how you and your DM interpret it, this could either give a shadow 1d6+1 strength damage, or 1d6 strength damage +1 negative energy.  If it's the first option, then it might be worth casting on your shadows.

11. Summoning

Summon Undead Class Ability (Sp):

First off, all of your summons are undead, flying, and incorporeal.  That means that your opponents need a +1 weapon to even hit them, and if the weapon isn't ghost touch then it has a 50% chance of having no effect.  Incorporeal and flying also means your minions are highly mobile, especially the more powerful ones with spring attack.  Being undead is generally a good thing as well, with its laundry list of immunities.

Shadow:

Theoretically you can summon one, use it to kill a commoner or a bag full of rats, and then rebuke that spawn and start your own army to take over the world.  Realistically, you won't get to do that, but you can use these guys to help your main guys flank, to quickly kill low-strength opponents, turning the weaker guards against the big boss.  They can also scout fairly well, though they won't set off many traps.

Very few monsters straight out of the MM can actually deal with shadows, though most DMs are smart enough to equip or buff opponents so you don't get free victories just for having incorporeal summons.    It's worth noting that shadows can work just fine in sunlight, unlike many other incorporeal undead.

More importantly, most of your higher level summons require a saving throw before the opponent takes any con/level drain, while the shadow automatically deals that damage when it hits.  For that reason, any time you're worried that a foe is going to have a massively high fort save (giants, dragons, etc), it's probably a good idea to summon shadows.
Skills: Hide +8*, Listen +7, Search +4, Spot +7

Wraith or 2 Shadows:

Wraiths are great against animals, as they automatically panic all animals within 30 feet, though it could annoy the party druid.  Constitution drain is good at all levels, though the save DC is pretty low.  Like shadows, these guys are good for killing low-level guys to make a fast army of spawn in your enemy's castle or something.  Their skills make them excellent scouts, and surprisingly good at some social skills like intimidate.  Not only that, but they can track stuff for you apparently.  Their major downside is that natural sunlight screws them over royally. 

In contrast, 2 shadows means you can easily set up flanking, compensate for being outnumbered, etc.  Again, shadows are a good choice if nothing is going to fail the con drain in the fight.

Skills: Diplomacy +6, Hide +11, Intimidate +10, Listen +12, Search +10, Sense Motive +8, Spot +12, Survival +2 (+4 following tracks)
In most cases, a single wraith is going to be better than a pair of shadows for the party.

Spectre, 2 wraiths, or 4 shadows:

A spectre is a small bump up from a wraith - more HD and 2 levels of energy drain compared with 1d8 constitution drain.  I'd use these against spell-casters and a pair of wraiths against almost anything else - but against a mob of weak creatures or a foe that your wraiths can't hit or with insane fortitude saves, 4 shadows are a good way to set up flanking, AOO's, and a quick source of strength drain.  Like wraiths, a spectre is powerless in sunlight.
Skills: Hide +13, Intimidate +12, Knowledge (religion) +12, Listen +14, Search +12, Spot +14, Survival +2 (+4 following tracks)

Greater Shadow, 2 spectres, 4 wraiths, or 4 shadows:

a greater shadow has a slightly better attack bonus and strength drain, but their coolest ability is that they pick up a few feats, specifically mobility and spring attack, allowing them to float through the floor, hit a foe, and escape again.  In most cases, summoning 4 wraiths or even 4 shadows each round is going to overwhelm an opponent much more quickly, but greater shadows certainly have their niche in a fight, especially if you have a few rounds to prepare.
Skills: Hide +14*, Listen +9, Search +6, Spot +9

Dread Wraith, 2 greater shadows, 4 spectres, 4 wraiths, or 4 shadows:

at 16HD, the dread wraith might actually survive an attempt from most turn undead effects and can take a hit or two from high level opponents.  With +16 to hit, it should succeed on nearly every attack, and a DC 25 fortitude save is pretty rough at level 13 for any monster with a weak fort save.  

The dread wraith also has a unique form of blindsight and a great touch AC, as well as the same spring attack shuffle as a greater shadow, and the best skills of any of your summons - perfect as a scout.  However, like a wraith it is powerless in sunlight.  Generally, these bad boys should out-perform 4 spectres in most fights, though if you're fighting in sunlight then 2 greater shadows are the best bet.  
Skills: Diplomacy +9, Hide +24, Intimidate +26, Knowledge (religion) +22, Listen +25, Search +22, Sense Motive +23, Spot +25, Survival +4 (+6 following tracks)

Summon Undead spell line: I like these spells, but they aren't very good for a MoS, who will be behind the curve on most of them.  Still, at 5th level the owlbear from Summon Undead II is still a decent meatshield, and there might be some other gems I've missed.

Summon Nature's Ally
In general, you will want to stay away from using SNA even as a spirit shaman or druid, as the creatures will rarely keep up with the CR you face.  

Summon Monster
While you will be a rank behind on summoning these, often the creatures on this list have good spell-like abilities, especially at higher levels.  See the handbook link at the top for more information.

12. Equipment

Cloak of Charisma +X

Nightsticks: it's almost always worth getting at least 1 if you use divine metamagic.

Rod, Metamagic: especially extend, lesser is a great bargain, but all of these rods have their uses.

Bag of Holding, Handy Haversack, Portal Hole, etc.  Use it to carry around snow, dead bodies, ghost touch weapons for your summons, whatever.

[Akalsaris]

13. Party Role

Battlefield Control/Disabler: this is probably where you will shine in most cases.  With lots of summons blocking the area up, you can usually provide flanking and force enemies to concentrate on your shadows if they want to get anywhere.  Depending on your dip, you might also have entangling, darkness, maneuvers, etc. as options as well.  This works especially well in conjunction with a prepared tank or damage dealer such as a crusader, who can benefit from the shadows to deal his damage more effectively.

Damage: level drain, constitution drain, and strength damage can drop unprepared foes pretty quickly.  You might not be a traditional damage dealer, but you'll be reducing your opponents' hit points through lost levels and constitution at a respectable rate.  This works especially well in conjunction with an offensive primary caster such as a necromancer buddy, who can hit your Con-drained and level-drained opponents with a high-DC save-or-die spell. 

Healer/Buffer: like it or not, you're a divine caster, and that means that sometimes people expect you to heal them.  Hopefully your summons will reduce the need for party healing by absorbing a few hits, but keep a wand of lesser vigor or CLW handy.  Since your spell-casting will lag behind a bit, your spells might also be best used to buff your summons and party members.  This works well in conjunction with a party of undead or dread necromancers, so that spells which heal your monsters will work on the party as well.

Necromancer: like normal clerics, you are an excellent necromancer without even spending feats and skills on it.  Dipping into necromancer for the ACF to improve the undead you create will make this even better.  This works best when your party isn't filled with paladins and druids, of course.  If your DM allows it, you might even be able to rebuke and control the spawn created by your summons, bolstering your incorporeal army with permanent followers.

Scout: your summons make superb (albeit short-lived) scouts, and with hide as a class skill, you can be a decent scout as well with the right dip class.  This works best if you can convince your DM to let your incorporeal summons be the same character each time, so you can re-summon and question them.    Remind your DM of the Shades from WCIII if he's played it.

Tank: your summons can tank for the party in a pinch, but with your slow spell progression, your summon undead spells will be pretty weak for the levels, and incorporeal creatures usually have low hit points.  As a wannabe cleric though, you're no slouch in the tanking department yourself either with the right buffs.  This works best in a party that has a lot of damage and battlefield control so that you don't take too many hits.

Trapfinder: if you're a beguiler, artificer, or spell-thief dip, or if you have the kobold domain, you can also be a trap-finder.  With the MoS's low skill points and class skill set, I'm not saying you should - but you can, if you want to be some kind of crazy triple threat character.

Social front: like the trapfinder, there are other classes that do it far better, but you are a charisma-based character with diplomacy as a class skill, and a single level of marshal or dragonfire adept can make you even better at the role.

14. Tactics
Here's some tactics by PhaedrusXY for a solo caster gauntlet:
http://forums.gleemax.com/showthread.php?p=14767223#post14767223

One thing to look into is a way to cast darkness & deeper darkness reliably, since that will let you summon wraiths and spectres outside during the day.  A dragonfire adept or a warlock dip can both net this ability.

Another thing to consider is that your incorporeal summons can occupy the same square as you or an ally, possibly granting concealment to the ally and cover to the shadows. 

Your shadows should always have a place to hide with you - in your shadow.

Since you're primarily a conjurer, Invisibility or the mundane Hide skill are both quite thematic and good for a MoS, as you can remain hidden while your summons gleefully tear opponents apart.

Illusions are another solid choice for spells if you can get them, since an opponent facing a pair of specres is quite unlikely to disbelieve a few shadows backing them up.  Since incorporeal undead make no noise, have no smell, and are pretty unfamiliar to most people, lower-level illusion spells can mimic them quite well.

Remember that  you're basically a cleric in terms of HP, BAB, saves, and spells.  That means you still rock at almost everything - don't limit yourself too much in feats.  Remember to animate the dead, to use diplomacy, fight with divine power, to scry on enemies - anything you can do as a straight cleric you can do about as well as a MoS.

15. Final Thoughts

One thing that occurred to me while making this guide is that there must be plenty of other prestige classes and feats that you can get early by multi-classing - and it might be a good idea to pair up on some of them.  For example, Vile Speech needs a base Will of +5 and Filthy Outburst needs a Will of +7, so with the vile feats from Elder Evils you could have a build that works something like this:

Human Cleric 1/Human Paragon 2/Master of Shrouds 3
Feats:
1st human: Spell Focus: Conjuration
1st character: Augment Summoning
1st vile: Chosen of Evil
3rd character: Dark Speech
3rd bonus human paragon: Dark Whispers
5th vile: Filthy Outburst
6th character: Insane Defiance

Books required: Libris Mortis, Elder Evils

[Akalsaris]

16. Sample Build Stubs

The builds I've made are only stubs, designed to help players think of possible starting points for their characters, and adapt them according to book list and personal taste.  Different and more detailed/optimized builds are greatly welcome. 

Core-only MoS
Halfling Cleric 2/Necromancer 1/MoS 10/Cleric 7
Feats: 
1st char: Spell Focus (Conjuration)
3rd char: Augment Summoning
Domains:
War
Luck
Books used: online preview of MoS or Libris Mortis, Core

Sample DMM MoS
Human Human Paragon 1/Cloistered Cleric 1/Human Paragon +1/MoS 1
Feats:
1st human: Spell Focus (Conjuration)
1st char: Augment Summoning
3rd bonus human paragon: Quicken Spell
3rd char: DMM: Quicken Spell
Domains:
Open, but Undeath and Planning are always great, and Knowledge is a bonus domain.  With a 16 Charisma, has 10 turn attempts: enough for 2 quickened spells/day.  Cloistered Cleric is good because you can better take advantage of the skills from Human Paragon.
Books used: Unearthed Arcana, Complete Divine

Diplomancer MoS
Human Cleric 2/Marshal 1/Master of Shades 1
Feats:
1st human: Spell Focus (Conjuration)
1st char: Negotiator
2nd bonus marshal: Skill Focus (Diplomacy)
3rd char: Augment Summoning
Domains:
Mind
Charm
Total: (Assumes Cha 18):
+7 ranks
+2 Negotiator
+3 Skill Focus
+4 Charisma
+4 Motivate Charisma
+4 Charm domain (+2 from 4 Charisma, +2 more from Motivate Charisma)
+2 domain
= +26 at 4th level (+25 at 3rd), and in another level you'll rock out with shadows anyways, providing you with a viable alternative to your diplomacy checks.  It's nothing earth-shattering, but it will certainly beat most non-combat encounters for most of the game.
Books used: Miniatures Handbook, Libris Mortis, Spell Compendium

Tome of Battle MoS
This character fights behind his summoned shadows and undead, using his martial abilities to augment their attacks.  He focuses on flanking with summons and maneuvers to overcome a poor BAB.
Human Swordsage 2/Cloistered Cleric 1/MoS 1
Feats:
1st human: Spell Focus (Conjuration)
1st char: Augment Summoning
1st bonus swordsage: Weapon Focus (spiked chain)
2nd bonus cleric: Knowledge Devotion
2nd bonus cleric: Fire Devotion
3rd char: Weapon Finesse (Spiked Chain)
Domains: War (Kossuth).  Kossuth grants Spiked Chain as a War domain choice, saving a feat.
Books used: Tome of Battle, Libris Mortis, Unearthed Arcana, FRCS, Complete Champion.  Cloistered Cleric meshes well with the swordsage's wisdom to light armor and 6 skills/level.

I rolled straight 8's and an 18...
This character is SAD (Single-attribute dependent), using his charisma for spell-casting, summoning, and to gain bonuses on stealth-related skills.  Cleric grants much-needed armor and shield proficiencies as well.
Strongheart Halfling Shugenja 1/Cleric 2/MoS 1
Feats:
1st character: Spell Focus (Conjuration)
1st bonus: Augment Summoning
3rd char: Any DMM or Devotion feat
Domains:
Charm
Halfling
Books needed: Spell Compendium, Libris Mortis, Complete Divine, FRCS

Sample character: this is the character build for a character I'm playing for a game set in the Warcraft III setting, where the players are cultists of the Lich King.  He fills the social face and healing roles, and also has some weak trap-finding and stealth skills.  At low levels, he summons water elementals and casts beguiler spells in a fight, while at higher levels his water elementals are generally replaced by incorporeal undead.  At 6th level, for example, he can summon around 14 medium water elementals and 10 shadows each day with a good charisma score and the Charm domain. 
Human Beguiler 1/Cloistered Cleric 2/MoS 3.
Feats:
1st character: Spell Focus (Conjuration)
1st human: Augment Summoning
2nd cleric: Water Devotion
2nd cleric: Knowledge Devotion
3rd char: Beckon the Frozen
4th MoS: Extra Turning
6th char: Cold-casting
Domains:
Charm
Books needed: Spell Compendium, Libris Mortis, Frostburn, Complete Champion, Unearthed Arcana

Another sample character: this is an alternative build I designed for the above character, which sacrifices versatility in party role for stronger low-mid level combat:
Human Cleric 2/Conjurer 1/MoS 3.
Feats:
1st character: Spell Focus (Conjuration)
1st human: Augment Elementals
1st cleric: Water Devotion
2nd bonus: Augment Summoning
3rd char: Beckon the Frozen
4th MoS: Extra Turning
Domains:
Charm
ACFs: trade familiar for an earth or air elemental (Complete Mage), trade Scribe Scroll for Augment Summoning (UA), possibly take Focused Specialist.
Books needed: Spell Compendium, Libris Mortis, Frostburn, Complete Champion, Unearthed Arcana, Complete Mage

With flaws:

Stealthy MoS
This character creates darkness as an immediate action, then at low levels breathes fire at his enemies, entangling them while he dances around in the darkness and hides.  At the mid-levels he has hide in plain sight and is nearly undetectable along with his shadows. 
Strongheart Halfling Dragonfire Adept 1/Cloistered Cleric 2/MoS 3
Feats:
1st halfling: Spell Focus (Conjuration)
1st char: Instinctive Darkness
1st flaw: Blend into Shadows
1st flaw: Entangling Exhalation
3rd char: Augment Summoning
6th char: Darkstalker
Domains:
Baator or Charm and Halfling (or a Devotion feat to spend turn attempts)
Note: retrain skills at later levels to move some previous skills to max Hide from MoS. 
Books needed: Drow of the Underdark, Dragon Magic, Races of the Dragon, Lords of Madness, Spell Compendium, Libris Mortis, Unearthed Arcana, FRCS

Draconic MoS
This character benefits from the venerable stats of a dragonwrought kobold.  Archivist MoS characters normally suffer from MAD, but the +3 to all mental statistics for dragonwrought kobolds turns that into an advantage.
Dragonwrought Kobold Cloistered Cleric 1/Archivist 2/MoS 1
Feats:
1st char: Spell Focus (Conjuration)
1st bonus domain ACF: Knowledge Devotion
1st  bonus domain: Extend Spell
1st bonus domain: Augment Summoning
1st flaw: Persistent Spell
1st flaw: Dragonwrought Kobold
3rd char: DMM: Persistent Spell
Domains:
Planning
Dragon Below 

Books needed: Races of the Dragon, Spell Compendium, Libris Mortis, Unearthed Arcana, Complete Champion, Eberron Campaign Setting

17. End of guide

All right, I think that's everything I've got.  Input is greatly appreciated, especially from players who have taken the MoS past 6th level.

[PhaedrusXY]

Nice! I didn't look through all of it yet, but it looks like you were very thorough. If I have time, I'll read through it more carefully and try to offer any constructive criticism I can think of. I'm glad someone picked this up. I just didn't have time to actually finish a real handbook on it.

[ChristopherGroves]

Mention of the Dynamic Priest feat would be goodness ...

[Surreal]

Something like Cleric 1/XYZ 2/MoS 2/Ur-priest 2/MoS +8 can also work. So you wind up with MoS abilities at the "intended" level, and you get the accelerated Ur-priest casting. Painful suckitude at level 6 though, until you get the rebuking from ur-priest 2 which re-qualifies you for MoS.

[Akalsaris]

Thanks Phaedrus

Chris, if you provide the details of the feat I'll add it.  It's the one from that Dragonlance splat book that makes Cha a main casting stat for some classes, right?

Surreal, I'll add a note on Ur-priest.  It skipped my mind because it delays the MoS summoning abilities, but would probably be solid at levels 9+, albeit not as ridiculous as some other ur-priest builds.  Maybe a cloistered cleric 1/warlock 2/MoS 2/ur-priest 2/eldritch disciple 10/XYZ would be good, especially if the MoS level could count towards ur-priest.  Over a cleric 1/warlock 4 entry it gains extra turning, summoning shadows, and possibly a spell level, but loses a least incantation and 1d6 EB.

[PhaedrusXY]

Something like Cleric 1/XYZ 2/MoS 2/Ur-priest 2/MoS +8 can also work. So you wind up with MoS abilities at the "intended" level, and you get the accelerated Ur-priest casting. Painful suckitude at level 6 though, until you get the rebuking from ur-priest 2 which re-qualifies you for MoS.

Make the XYZ Dread Necro, and it will be alot less painful.