This is the most dedicated Fiend of Possession build. Everything is focused on you getting around without ever making yourself seen. Any race is possible, therefore I will stick to 16 levels for the base build if you don’t have access to the above entry tricks.
Beguiler 1/ Telepath 1/Bloodline 1/ Marshall 1/ FoP 1/ Bloodline 1/ FoP 5/ Bloodline 1/ Uncanny Trickster 2/ Mindbender 1/ Thrallherd 1/
Kaori/ Abyssal Skulker 2HD/ 2 LA
Human Replace Uncanny Trickster with 6 levels of Legacy Champion
Bladeling+Divine Minion 2 LA/ Fiend of Corruption 1/ Uncanny Trickster 1
L1 Otherworldly (If needed)
L3 Martial Study (Shadow Hand)
L4 Skill Focus Diplomacy
L9 Least Legacy (If needed)
Devil L2 Dodge, L14 Alterness ( Cha, Con, Int +1)
Genie, Efreeti L2 Improved Initiative, L 8 Dodge (Str, Cha, Dex +1)
Vampire L2 Stealthy, L10 Lightning Reflexes, L12 Alterness, L14 Improved Initiative (Str, Cha, Dex +1)
Psionics are perfect since most of them are purely mental actions, which the FoP can perform while possessing an object or person. There are two main options. Go for the straight forward telepath which is more versatile but losses out on high level powers. Or go for the limited power list and play an ardent. I listed the Illumian as the race of choice, but this depends on wether your DM uses psion/magic transparency. The +2 caster level would work great for your manifestor level.
Telepath 5/ Thrallherd 1/ FoP 6/ Thrallherd 8
L3 Practiced Manifestor
L5 Alternative Class Feature, Telepathy (25 Ft)
Ardent 5/Thrallherd 1/FoP5/Thrallherd 9
L3 Extra Power
L6 Practiced Manifestor
This is just a straight forward FoP build with chameleon thrown in for all of its usual tricks.
Beguiler 1/ Human Paragon 2/ FoP 2/ Mindbender 1/ FoP 4/ Chameleon 10
L1 Able Learner
L3 Improved Sigil
(I will check that line and see the specifics uses of it.
Savage Bard 1/ Monk 1/ Bloodline 1/ Savage Bard 1/ FoP 6/ Ur-Priest 2/ Mystic Theurge 8Phaerimm Trickery
Phaerimm’s have the nifty ability to cast their sorcerer spells as spell-like abilities without somantic, vocal, or material components. Use the ritual of alignment as before.
Phaerimm, Hatchling 2HD +2LA/Sorceror 1/ FoP 4/Sorc 1/ Incantratrix 10
L3 Iron Will
L6 Sanctum Spell
L9 Practiced Spellcaster
As shown, the build only gains access to 7th level spells. If level buy-off is available, you can drop the 2 LA and 2 FoP levels to get 9th level spell access. A similar build can be made with a Sharn granting 15th level progression in sorc and favored soul.
4HD+5LA/1 Mystic Theurge/ 2 FoP/ 8 Mystic theurge
Shadowcraft Mage, FoP light
The illusion flavor of the master specialist gets free still, silent, and eschew materials with illusion spells, but not until level 10 in the class. You can always switch the order of Master Specialist and Shadowcraft mage.
3 Wizard/ 3 Master Specialist/ 2 FoP/ 7 Master Specialist/ 5 Shadowcraft Mage
L3 Spell Focus Illusion
L4 Spell craft skill focus (Master Specialist Bonus)
L6 Martial Maneuver (Shadow hand)
L6 Greater Spell Focus Illusion (Master Specialist Bonus)
9th level spells and a caster level of 20 with all the normal shadowcrafter mage goodness.
Warlocks and Eldritch blast
I originally did not think warlock would work well since the invocations are spell-like abilities that require somantic components. Notice though that eldritch blast is not an invocation but is a spell-like ability. Bingo, you can blast while in the object, just not add an invocations on the fly. Luckily Hellfire warlock also saves the day by boosting your damage by 12d6 (don’t forget bloodlines).
Theoretical buildsCleric and a half
Warlock 2/Bloodline 1/Binder 1/ FoP 1/Bloodline 1/ FoP 5/Bloodline 1/Warlock 4/ Hellfire warlock 2/Mindbender 1/Hellfire warlock 1
L3 Martial Study (Shadow Hand)
L18 Mindsight (Feat Shuffle)
The idea here is to be a full cleric/wizard and a FoP. We are going to use the usual Other Worldly/ritual of alignment for entry to FoP. Afterwards we are going to enter the Eldrich Master PrC from dragon mag #280. It does not progress spell casting, but grants a bonus spell slot 1 level higher than you can currently cast and bonus metamagic feat at level 3. Add this slot to cleric to pick up level 2 spells. Then at level 4 it lets you add a spell list from another casting class to your exsisting spell casting classes. These spells are all cast as arcane spells regardless of how the spells are usually cast. That means you cleric is now both an arcane and divine casting class. Use Mystic Theurge then to double progress the class. You end up with 9th level spells cast off of one stat and set of spells slots, but come from both the cleric list and another list of your choice (probably wizard). Use Arcane thesis for orb of force of another spell of choice to get free still and silent spell added for free.
Cleric 1/ Wu Gen 1/ Cleric 1/FoP 5/Eldrich Master 4/Mystic Theurge 8
L1 Other Worldly
L1 Extend Spell (Human)
L2 Persistent Spell (Wu Gen)
L3 Eschew materials
L6 Divine Metamagic
L9 Easy Metamagic Persistent Spell
L12 Still Spell
L12 (EM Bonus) Silent Spell
L18 Arcane Thesis
Domains of interest:
Undead for Extra Turning
Planning for Extend Spell
Fiends of Possession make optimal cohorts for characters of the appropriate alignment. The key feature is their ability to augment your character and remain out of sight. One of the biggest problems I have with leadership is picking a cohort that is useful, out of the way, and does not overshadow other party members.The Fixer
This cohort can make any armor, ring, weapon, or wonderous item, plus buy and sell things at the best prices. You can leave him at home when you want or take him on the go. The xp mechanic with leadership makes the cohort useful even after he hits his max level, just continue to burn the xp or hide it with the link below.
Midguard Dwarf 8 HD +4LA/ FoP 5
L1 Mercantile (if available)
L3 Item Familiar (if available)
L6 Master Artisian or eberron crafting feat
L9 Master Artisian or eberron crafting feat
L12 Master Artisian or eberron crafting feat
Sanctify relic might be of interest if your main character is a divine caster. http://www.wizards.com/default.asp?x=dnd/we/20060526a
The standard FOP build in the two sections above is the other optimal cohort build.