Ok, Tshern. So neither of those would be a vestige in your campaign? But I could use their powers, and maybe reflavor their origin or something? Or would I still draw power from the actual Geryon of your campaign as a vestige?
There are a couple of vestiges called Astaroth that are in different sources. One of these is supposedly a fallen angel, and the other was the "demon lord" I already mentioned, which is actually Garhauth in your game. Maybe we should rename one or both... I could PM you a pdf with the vestiges outside of Tome of Magic in it, if you're interested. It has both of the Astaroths in there.
Just for reference, here are brief descriptions of the abilities of the vestiges I'm likely to use. The stuff in parenthesis is a brief description of the influences they'll have on me while bound (the physical stuff is automatic; the mental stuff after the semi-colon is only if I fail the binding check). I also put brief explanations of who they are in parenthesis for some of them (Geryon and the two Astaroths). Several of these are powerful demons that are imprisoned in a part of the abyss called the Wells of Darkness. I think this is from the Savage Tides adventure path (Dragon 357). I'll mark them with an asterisk. From their descriptions, I wonder if they didn't accidentally put the Divination power under Astaroth instead of Cabiri, since Cabiri is all about scrying and divination. I plan to keep Balam bound pretty much all the time, and bind the others as needed (it only takes a minute or two to bind one, but it is alot trickier to "unbind" them).
Acerak (gem tooth; must grab for power): Detect & Hide from Undead, Immunity to cold and electricity, Paralyzing Touch (Fort DC 19 each round, 5 rounds), Speak with Dead (at will, DC 19)
Astaroth (fallen angel)(stench, yellowed skin): http://www.wizards.com/default.asp?x=dnd/we/20070307a
Bardic Knowledge, Stinking Cloud breath; +4 Dipl, Bluff, and Intimidate; all crafting feats if I meet prereqs, Suggestion 1/5 rnds
Astaroth* (demon lord)(stench, cloudy eyes; MUST ATTACK DEVILS): Blackflame (fire damage is half vile), Divination (as spell, CL=EBL), +4 bluff and disguise vs evil outsiders, attacks count as silver
Ahazu* (void mouth; kleptomaniac): Blindsight (5 ft/EBL)!, Ahazu's Abduction (remove enemy from play for 1 round, at will, Will negates), Unholy Blight touch 1/5 rnds, Void Mind (Mindblank + immunity to soulbind, magic jar, etc)
Balam (hollow, guttural voice; hates clerics): reroll an attack, save, or skill check once every 5 rounds; 2d6 cold gaze (will negates); Prescience (+1/4lvls insight to Ref, AC, and Initiative); Weapon Finesse
Buer (hooves; forgetful, hates to kill): healing touch, fast healing, disease and poison immunity (30 foot RADIUS), Track, +4 Know (nature, untrained), +4 survival
Cabiri* (Dragon 357)(third eye; wants to see everything) - Arcane Eye (as spell, 1 sensor, at will), Far-seeing Gaze (+10 Scrying DCs), Seer in Darkness (add 60 ft to darkvision range, gain low-light vision), Visons of Terror (Phantasmal Killer 3/day); +4 insight vs figments, -4 vs patterns, cannot avert eyes from Gaze attack
Dantalion (face on torso; must read thoughts of leaders): Sanctuary, Read Thoughts, teleport 50' 1/5 rnds, +8 knowledge
Geryon (eyes around head; become overly trusting)(former Lord of the 9): +4 spot and search, swift fly 60' 1/5 rnds, see in darkness, all-around-vision, acidic gaze (30', 2d6, will negates)
Malphas (black teeth and tongue; overly romantic, must use poison if possible): Move action invisibility, summon dove/raven, Poison Use, Sudden Strike (3d6)
Naberius (gravelly voice; loves to give speeches): take 10 bluff and dipl, rushed, Command (as spell), heal ability damage 1/round, Disguise Self at will, gain use of (Con mod) trained-only skills you have no ranks in
Otiax (blue fog; nervous around closed doors and must open locks): Combat Reflexes, Concealing Mist (personal concealment), Open Portal (swift action), Unlock (up to DC 20), Air Blast (2d6 touch attack, 10 ft range)
Paimon (stretched mouth; lascivious and bold, must dance if hear music): Whirlwind Attack, pseudo-dervish dance, +4 dex, tumble +4
Sorry for all the questions. I do think these could add an interesting dimension to the game, though, and want to get the flavor right for your campaign. I don't want to take away from your posting to the main thread, though.