Acolyte of the Skin

The description can be found in Tome & Blood:

The ACOLYTE OF THE SKIN

Class Level	Base Attack Bonus	Fort Save	Ref Save	Will Save	Special	Spells per Day
1	+0	+2	+0	+2	Wear fiend
2	+1	+3	+0	+3	Flame resistant	+ 1 level of existing class
3	+1	+3	+1	+3	Fiendish glare
4	+2	+4	+1	+4	Fiendish knowledge	+ 1 level of existing class
5	+2	+4	+1	+4	Skin adaptation
6	+3	+5	+2	+5	Cold resistant	+ 1 level of existing class
7	+3	+5	+2	+5	Glare of the Pit
8	+4	+6	+2	+6	Fiendish knowledge	+ 1 level of existing class
9	+4	+6	+3	+6	Summon fiend
10	+5	+7	+3	+7	Symbiosis	+ 1 level of existing class

Flame Resistant (Ex):
At 2nd level, the fiendish skin binds tighter, granting the acolyte fire resistance 20.
Fiendish Glare (Su):
At 3rd level, the acolyte of the skin gains the supernatu­ral ability to unnerve op­ponents with a ferocious glare once per day. This is not a gaze attack, and the target need not meet the acolyte's eye. Glaring is a standard action that affects any creature he can see within 100 feet. Opponents must succeed at a Will save (DC 20) or be appalled by the terrible promise of retribution in the acolyte's eyes, suffering a -2 morale penalty to attack rolls, damage rolls, and saving throws for 10 minutes. A creature with 50 or fewer hit points is also stunned for 3d4 rounds, one with 51 to 100 hit points is stunned for 2d4 rounds, and one with 101 to 150 hit points is stunned for 1d4 rounds. A creature with 151 hit points or more is not stunned but still suffers the -2 morale penalty if it fails its saving throw.
Fiendish Knowledge: The fiendish skin whispers promises of great power, and to prove it, reveals a hitherto unknown ability At 4th and 8th level, the acolyte chooses a bonus feat for which he already meets the prerequisites.
Skin Adaptation (Su): By 5th level, skin and wearer have grown more comfortable together, as if they had never been separate. The natural armor bonus granted by the fiendish skin increases to+ 2, the acolyte's darkvision improves to a 120-foot range, and he can now use poison twice per day as cast by a 16th-level caster. In addition, the acolyte gains an inherent+ 2 modifier to Constitution.
Cold Resistant (Ex): At 6th level, the fiendish skin confers cold resistance 20.
Glare of the Pit (Su): At 7th level, the acolyte gains the supernatural ability to produce fiery rays from his eyes. Once per day as a standard action, he can project two rays (one from each eye) with a range of 100 feet. He may aim both at one target, or one each at two different targets, by making a ranged touch attack. A ray that hits the target deals 8d6 points of fire damage. If both rays hit the same target, the damage is 16d6.
Summon fiend (Sp): At 9th level, the acolyte learns to draw on another power of his fiendish skin. If the skin is demonic, once per day he can attempt to summon a vrock with a 35% chance of success; if devilish, once per day he can attempt to summon a gelugon with a 35% chance of success. The summoned creatures do the acolyte's bidding but automatically return whence they came after 1 hour. A fiend that has just been summoned cannot use its own summon ability for 1 hour. At the DM's discretion, using this power leaves the acolyte beholden to the summoned fiend.
Symbiosis: At 10th level, the fiendish skin and the acolyte are one, and only final death can separate them. His type changes to "outsider," which means (among other things) that he is no longer affected by spells that specifically target humanoids, such as charm person, but he can be hedged out by a magic circle spell against his alignment. Additionally, the acolyte gains damage reduc­tion 20/+ 1.

Wear Fiend (Su): An acolyte of the skin summons the essence of a fiend to himself and wears it like a second skin. The Ritual of Bonding is painful and not be undertaken lightly. The ritual requires 10 rounds from initi­ation to completion, and once begun, nothing can halt its progress. The fiendish essence subsumes the caster's own skin, an agoniz­ing process that deals 1d4 points of damage each round of the ritual—wise candidates keep some cure potions on hand.
At the end of the rite, the acolyte's skin sports an oily, almost unnoticeable sheen. However, as he gains addi­tional levels of the prestige class, his skin darkens, sprouts spikes, and gradually gives the wearer a fiend­ish visage. The fiendish essence also begins to whisper foul secrets to its wearer, urging him to evil. (The wearer may accept or ignore this advice according to his temperament.)
The bonded fiendish skin is for all intents and purposes the character's own. It grants the acolyte of the skin a + 1 natural armor bo­nus, a+ 2 inherent modifier to Dexter­ity, 60-foot dark­vision, and the spell-like ability poi­son once per day as cast by a 16th-level caster.

Epic progression can be found here http://www.wizards.com/default.asp?x=dnd/ei/20021208a

Thanks to Aristey for the info