http://brilliantgameologists.com
March 24, 2017, 11:53:53 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: These boards are now READ ONLY. We've started over! So don't try posting here. Go here www.minmaxboards.com
 
   Home   Help Search Members Login Register  
Pages: 1
  Print  
Author Topic: The Opposed Checks Handbook  (Read 6241 times)
0 Members and 1 Guest are viewing this topic.
Garryl
Hong Kong
****
Posts: 1240


« on: December 21, 2010, 06:45:13 PM »

Coming soon, a handbook all about opposed checks. How to win them. How to cause them. How to calculate the damn math correctly.

This will be more of an analysis of the mechanics than a usual guide to making it perfect. There will be some of that, but opposed checks are a broad enough mechanic that trying to cover everything is far more than one guide should have. Most of this will be math and analysis, but there will also be some about general techniques to boost the more common types of opposed checks and a few more specific, interesting or obscure things.

Really, the main reason I'm making this is for the math to be readily available for anyone that wants it.



Things that use opposed checks
Disarm/Sunder: Opposed attack rolls. +4 bonus for two-handed weapons, -4 penalty for light weapons. Also another +4 per size category difference to the larger opponent.
Bull Rush/Overrun/Trip: Opposed Strength checks. +4 bonus for each size category above Medium, -4 for each one below. Defender can oppose your Strength with Dexterity instead for trips.
Grapple: Opposed grapple checks. Uses BaB + Strength, with a +4 bonus for each size category above Medium, -4 for each one below. Too many options makes this a pain to follow, especially when they aren't even consistent on what actions they use.

Bluff: Opposed by Sense Motive for telling lies. Opposed by the sum on Sense Motive and BaB for feinting, so it really sucks against anyone with a few ranks in the skill and a good BaB, not to mention that feinting is usually unimpressive unless you have something really special.
Diplomacy: Mostly uses flat DCs, but arguing against someone is an opposed check. Useful to protect against Diplomancers.
Disguise: Opposed by Spot. Really easy to boost with shapechanging magic.
Escape Artist: Can be opposed by someone else's Use Rope check if you're tied up and trying to escape. One of the few cases where you can take 20 on an opposed check. Since the Use Rope check is amde well in advance and persists until the situation chenges, it's almost like rolling against a fixed DC. Note that the rope user gets a +10 bonus, so you'll probably lose on a tie.
Forgery: Forging something can only be detected by an opposed Forgery check. Despite the fact that your check is fixed when you forge the document, opponents cannot retry so they can't take 20.
Hide: Opposed by Spot.
Intimidate: Opposed by a modified level check.
Listen: Opposed by Move Silently.
Move Silently: Opposed by Listen.
Sense Motive: Opposed by Bluff.
Sleight of Hand: Stealing something is a flat DC and an opposed check (vs. Spot) at the same time. Hiding a weapon or object is opposed by Search (or Spot if they see you doing it), and gets various bonuses based on your clothing and the object being hidden.
Spot: Opposed by Disguise or Hide, as appropriate. Occasionally opposed by Sleight of Hand, but only to notice it, not to stop it.
Use Rope: Opposed by Escape Artist to tie soemone up, but you get a massive +10 bonus. On the other hand, they can take 20.

Initiaitve: Not technically an opposed check, but functions alot like one. Special mention due to its similarity and importance.
Charisma: Special mention due to its use with charm spells and planar binding spells.

Opposed Rank Checks: For deities going up against other deities. This can have significant effects on a victory and there are a few things that specifically affect the way this works. Utterly irrelevant in most games.


Notes:
Fate Mantle - Add your level in the class that granted you mantles to any d20 roll 1/day.
Competition Domain - Get a +1 bonus on all opposed checks.
Pride Domain - Reroll 1s. Less useful here than elsewhere, but still roughly equivalent to a +0.5 bonus. Saves only, and I don't think there are any opposed saving throws outside of homebrew.
Luck Domain - Reroll any die 1/day. Always useful.
Rerolls - Always useful, particularly with the variable target number of opposed checks.
Surge of Malevolence - Gives a bonus based on your Depravity/Corruption (don't remember which) once per day. Maxes out at a +9 bonus.

Reroll Wars - Can happen when you and your opponent can both reroll things after determining the result. Whoever has the most rerolls available holds an advantage, but static modifiers count more the more rerolls are involved (and thus the higher average die roll).

Skill Mastery - If you can take 10, it's like your opponent is making a fixed DC check, except that you can still have an advantage on a tie (thus forcing him to beat the "fixed DC" rather than just meet it). You only need a +10 modifier instead of +19 to assure victory this way. Worse than rolling if your relative modifier is +3 or less. Better than rolling if your modifier is +5 or better. Breaks even at a +4 relative modifier (70% success either way). However, taking 10 may prevent you from rerolling, which is a bad thing, especially in reroll wars when taking 10 would only give you a small advantage compared to rolling.
Savvy Rogue - Lets you take 12. Actually, gives you a +2 bonus when you take 10 (which is even better if you've got a relative modifier between -2 and +0). Makes "Taking 12" better than rolling with a relative modifier all the way down to -7 (before including the +2 taking 10 bonus). The difference isn't huge down there, but it's amazing the diference in range of usefulness.

Disarm/Sunder - Unlike PA and Strength bonuses, the +/-4 modifier cares about the kind of weapon, not how you wield it (ie: you get the +4 bonus only if you're actually using a two-handed weapon, not just using a one-handed weapon in two hands).

Rerolling - Rerolling after you know the results is interesting because it makes the opposed check into two parts. The initial roll follows the usual math for opposed checks. The reroll follows the usual math for fixed DCs instead (with the exception of tie breakers), since you know what your opponent's roll is.
« Last Edit: January 20, 2011, 12:25:37 AM by Garryl » Logged

A Guide to Free D&D - A resource of free, official D&D resources on the web.
General listing of my homebrew.
Links to things I've worked on
Idiot Crusader, refreshing maneuvers for free every round.
The Opposed Checks Handbook - Under construction.
Adaptations Handbook - Under construction.
Garryl
Hong Kong
****
Posts: 1240


« Reply #1 on: December 21, 2010, 06:45:24 PM »

The mechanics:
Opposed Checks
An opposed check is a check whose success or failure is determined by comparing the check result to another character’s check result. In an opposed check, the higher result succeeds, while the lower result fails. In case of a tie, the higher skill modifier wins. If these scores are the same, roll again to break the tie.

If two or more combatants have the same initiative check result, the combatants who are tied act in order of total initiative modifier (highest first). If there is still a tie, the tied characters should roll again to determine which one of them goes before the other.

Thus, you need to beat your opponent's total by 1 if you have a lower modifier, or tie if you have a higher modifier. You need a +19 modifier (compared to your opponent's modifier) to always win.


The math:


---How high a relative modifier you need to win unequivocally---
Your   Opponent's Roll
Roll    1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20
 1    +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9 +10 +11 +12 +13 +14 +15 +16 +17 +18 +19
 2     +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9 +10 +11 +12 +13 +14 +15 +16 +17 +18
 3     -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9 +10 +11 +12 +13 +14 +15 +16 +17
 4     -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9 +10 +11 +12 +13 +14 +15 +16
 5     -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9 +10 +11 +12 +13 +14 +15
 6     -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9 +10 +11 +12 +13 +14
 7     -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9 +10 +11 +12 +13
 8     -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9 +10 +11 +12
 9     -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9 +10 +11
10     -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9 +10
11     -9  -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9
12    -10  -9  -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8
13    -11 -10  -9  -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7
14    -12 -11 -10  -9  -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6
15    -13 -12 -11 -10  -9  -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5
16    -14 -13 -12 -11 -10  -9  -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4
17    -15 -14 -13 -12 -11 -10  -9  -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3
18    -16 -15 -14 -13 -12 -11 -10  -9  -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2
19    -17 -16 -15 -14 -13 -12 -11 -10  -9  -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1
20    -18 -17 -16 -15 -14 -13 -12 -11 -10  -9  -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*

*You can have a +0 modifier here instead of +1, but then you reroll the check instead of winning. You only have a 50% chance of winning on this reroll, due to equal modifiers.


---Your odds of winning based on your modifier---
Your
Relative  Chance of
Modifier  Winning
-19/less  zilch      0%
-18         1/400    0.25%
-17         3/400    0.75%
-16         6/400    1.5%
-15        10/400    2.5%
-14        15/400    3.75%
-13        21/400    5.25%
-12        28/400    7%
-11        36/400    9%
-10        45/400   11.25%
-9         55/400   13.75%
-8         66/400   16.5%
-7         78/400   19.5%
-6         91/400   22.75%
-5        105/400   26.25%
-4        120/400   30%
-3        136/400   34%
-2        153/400   38.25%
-1        171/400   42.75%
+0        200/400   50%
+1        229/400   57.25%
+2        247/400   61.75%
+3        264/400   66%
+4        280/400   70%
+5        295/400   73.75%
+6        309/400   77.25%
+7        322/400   80.5%
+8        334/400   83.5%
+9        345/400   86.25%
+10       355/400   88.75%
+11       364/400   91%
+12       372/400   93%
+13       379/400   94.75%
+14       385/400   96.25%
+15       390/400   97.5%
+16       394/400   98.5%
+17       397/400   99.25%
+18       399/400   99.75%
+19/more  always   100%



Taking 10

---How high a relative modifier you need to win when taking 10---
Your   Opponent's Roll
Roll    1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20
10     -8  -7  -6  -5  -4  -3  -2  -1  +0 +1*  +1  +2  +3  +4  +5  +6  +7  +8  +9 +10

*You can have a +0 modifier here instead of +1, but then you reroll the check instead of winning. Assuming you still take 10, your opponent has a 10 chances of winning out of 19 (a roll of 10 for him is a reroll in the same situation again) or rather you have 9 chances out of 19 to win (a 52.63% chance of him winning, 47.37% chance for you winning).


---Your odds of winning when taking 10 based on your modifier---
Your
Relative  Chance of
Modifier  Winning
-9/less   zilch      0%
-8         1/20      5%
-7         2/20     10%
-6         3/20     15%
-5         4/20     20%
-4         5/20     25%
-3         6/20     30%
-2         7/20     35%
-1         8/20     40%
+0         9/19     47.37%
+1        11/20     55%
+2        12/20     60%
+3        13/20     65%
+4        14/20     70% ***Break even point.
+5        15/20     75%  | Always take 10 if your relative
+6        16/20     80%  | modifier is +5 or better
+7        17/20     85%  |
+8        18/20     90%  |
+9        19/20     95%  |
+10/more  always   100%  V



« Last Edit: December 22, 2010, 12:51:42 AM by Garryl » Logged

A Guide to Free D&D - A resource of free, official D&D resources on the web.
General listing of my homebrew.
Links to things I've worked on
Idiot Crusader, refreshing maneuvers for free every round.
The Opposed Checks Handbook - Under construction.
Adaptations Handbook - Under construction.
Garryl
Hong Kong
****
Posts: 1240


« Reply #2 on: December 21, 2010, 06:46:22 PM »

Class Features and stuff:
Domains - Clerics get 2 domains. Contemplative can give another domain or two. Those are the two most commonly used sources.
Competition Domain: +1 bonus on all opposed checks.
Luck Domain: Gives a reroll of anything 1/day.
Pride Domain: Reroll natural 1s. Not as good as elsewhere, but still roughly equivalent to a +0.5 bonus.
Travel Domain: Free and automatic Freedom of Movement effect. Automatically wins you the opposed grapple check to escape or avoid a grapple.

Skill Mastery - Lets you take 10 on a number of skills. Rogues can pick it up at 10th. Swashbucklers get it from a few skills, too. Exemplar is another biggie. See the math section for the details of when and why taking 10 is good for you.
   If you can take 10, it's like your opponent is making a fixed DC check, except that you can still have an advantage on a tie (thus forcing him to beat the "fixed DC" rather than just meet it). You only need a +10 modifier instead of +19 to assure victory this way. Worse than rolling if your relative modifier is +3 or less. Better than rolling if your modifier is +5 or better. Breaks even at a +4 relative modifier (70% success either way). However, taking 10 may prevent you from rerolling, which is a bad thing, especially in reroll wars when taking 10 would only give you a small advantage compared to rolling.
   The Savvy Rogue feat lets you "take 12". Actually, gives you a +2 bonus when you take 10 (which is even better if you've got a relative modifier between -2 and +0). Makes "Taking 12" better than rolling with a relative modifier all the way down to -7 (before including the +2 taking 10 bonus). The difference isn't huge down there, but it's amazing the diference in range of usefulness.
 
Mantles - The "domains" of psionics, most give small bonuses. Available by default to Ardents, and with ACFs to almost everyone else.
Fate Mantle: Add your level in the class that granted you mantles to any d20 roll 1/day. Big bonuses are even more necessary here to ensure victory than against a fixed DC.
Time Mantle: +2 initiative never hurts.

Auras - Marshal auras can give large bonuses to a variety of things.
Art of War: Adds your Cha bonus to everyone's disarm, trip, bull rush, and sunder attempts. That's opposed attack rolls, Str checks, Str checks, and attack rolls, respectively.
Motivate Dexterity: King of the motivate series of minor auras unless you're going for soemthing specific. Adds your Cha mod to everyone's Dex checks, Dex skills, and Initiative. Everyone rolls initiative, and while it isn't technically an opposed check, the mechanics are very similar.
Motivate Str/Dex/Con/Int/Wis/Cha: Adds your Cha bonus to everyone's {Stat} checks and {Stat} skills.

Battle Skill - Warblade 11th, +Int as insight to oppose bull rush, disarm, feint, overrun, sunder, and trip attempts.


Feats and stuff:
Improved Bull Rush/Disarm/Grapple/Sunder/Trip: Gives you a +4 bonus on the relevant checks for these maneuvers. Note that Imp. Feint does not give you a +4 bonus, despite having a similar name and function.

Weapon Focus, Knowledge Devotion, and other attack roll boosters: Only mentioned because Disarm and Sunder use opposed attack rolls.

Items and stuff:
Doomwarding weapon property: Gives 7 charges that can't be restored. Each charge can be spent to reroll anything. Costs +35000g on a weapon, so only +700g on an arrow. A bargain at ~160g per reroll.

Phaant's Luckstone: Gives a single reroll (as the Luck domain). You don't even need to hold it, just have it in your posession. Costs 1000g each.

Flails and other disarming weapons: You can get a nice little +2 bonus on your opposed attack roll for your Disarm attempt with these weapons. Don't overlook the benefit of using a two handed weapon instead. If you can get both, the more the merrier. See also Spiked Chain, Dire Flail, Heavy Flail, Nunchaku, Ranseur, Sai (+4 bonus, but it's light so meh), and Whip. A special shoutout goes to the Flindbar from MM3 and Shattered Gates of Slaughtergarde. It's only a one-handed weapon, but it gets the bonus and gives you a free disarm attempt on a critical. Also worth mentioning is the Gnomish Swordcatcher (RoS); it's one-handed but gives a +4 bonus on disarms, making it as good as a non-disarming two-handed weapon.

Locking Gauntlet: A whopping +10 on your opposed attack roll to avoid being disarmed. That's enough to negate the bonuses from a two-handed, disarming weapon wielded by someone with Imp. Disarm!




Reserved.

Feel free to post. I'll be updating this over the next few days.
« Last Edit: January 20, 2011, 12:31:53 AM by Garryl » Logged

A Guide to Free D&D - A resource of free, official D&D resources on the web.
General listing of my homebrew.
Links to things I've worked on
Idiot Crusader, refreshing maneuvers for free every round.
The Opposed Checks Handbook - Under construction.
Adaptations Handbook - Under construction.
The_Mad_Linguist
Organ Grinder
*****
Posts: 8780


Simulated Thing


« Reply #3 on: December 21, 2010, 08:46:06 PM »

Phaant's luckstone from ghostwalk gives a single luck domain reroll for 1k.

Doomwarding weapon enhancement gives seven rerolls of anything.
Logged

Linguist, Mad, Unique, none of these things am I
My custom class: The Priest of the Unseen Host
Planetouched Handbook
Want to improve your character?  Then die.
PhaedrusXY
Organ Grinder
*****
Posts: 8022


Advanced Spambot


« Reply #4 on: December 21, 2010, 09:05:40 PM »

Numbers and a graph to fill in your % chance of winning chart:

My numbers are slightly different from yours, for some reason...
« Last Edit: December 21, 2010, 09:07:33 PM by PhaedrusXY » Logged

A couple of water benders, a dike, a flaming arrow, and a few barrels of blasting jelly?

Sounds like the makings of a gay porn film.
...thanks
Garryl
Hong Kong
****
Posts: 1240


« Reply #5 on: December 21, 2010, 09:13:29 PM »

Yeah, I know those numbers. That graph assumes that every tie is rerolled. However, the rules actually include a tiebreaker other than rerolling. The higher modifier wins in a tie, and only forces a reroll if they are equal.

Edit: The math for that graph should be...
Let D = the difference between you modifier and your opponent's.
If D > 0
%success = ((20-D)^2+(20-D))/(2*(380+D))
else If D < 0
%success = 50%-((20+D)^2+(20+D))/(2*(380-D))
else
%success = ((20-D)^2+(20-D))/(2*(380+D)) = 50%
« Last Edit: December 21, 2010, 09:23:57 PM by Garryl » Logged

A Guide to Free D&D - A resource of free, official D&D resources on the web.
General listing of my homebrew.
Links to things I've worked on
Idiot Crusader, refreshing maneuvers for free every round.
The Opposed Checks Handbook - Under construction.
Adaptations Handbook - Under construction.
PhaedrusXY
Organ Grinder
*****
Posts: 8022


Advanced Spambot


« Reply #6 on: December 21, 2010, 09:20:15 PM »

It's really interesting that even a small advantage can give you a substantial chance of winning. So especially in the case of opposed rolls, those +1's and +2's do add up.
Logged

A couple of water benders, a dike, a flaming arrow, and a few barrels of blasting jelly?

Sounds like the makings of a gay porn film.
...thanks
Garryl
Hong Kong
****
Posts: 1240


« Reply #7 on: December 21, 2010, 09:29:01 PM »

The change in chance for success matters more for the first point and decreases linearly the further from 0 you go. The first point counts for so much more because it also seizes the ties for you.

Let D = the difference between you modifier and your opponent's.
If D >= 1
change in %success for next +1 modifier = (20-1-D)/400
else If D < -1
change in %success for next +1 modifier = (20+D)/400
else If D == -1 or D == 0
change in %success for next +1 modifier = (19+(20/2))/400 = 29/400 = 7.25%
« Last Edit: December 22, 2010, 11:21:30 AM by Garryl » Logged

A Guide to Free D&D - A resource of free, official D&D resources on the web.
General listing of my homebrew.
Links to things I've worked on
Idiot Crusader, refreshing maneuvers for free every round.
The Opposed Checks Handbook - Under construction.
Adaptations Handbook - Under construction.
snakeman830
Organ Grinder
*****
Posts: 3494


BG's resident furry min/maxxer

591915459 snakeman830@yahoo.com snakeman830 snakeman830
« Reply #8 on: December 27, 2010, 07:29:16 AM »

Pride Domain only lets you re-roll on saving throws.
Logged

I am constantly amazed by how many DM's ban Tomb of Battle.  The book doesn't even exist!

Quotes:
By yes, she means no.
That explains so much about my life.
hiicantcomeupwithacharacterthatisntaghostwhyisthatamijustretardedorsomething
Why would you even do this? It hurts my eyes and looks like you ate your keyboard before suffering an attack of explosive diarrhea.

If using Genesis to hide your phylactry, set it at -300 degrees farenheit.  See how do-gooders fare with a liquid atmosphere.
Pages: 1
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2008, Simple Machines LLC Valid XHTML 1.0! Valid CSS!