Illo sells tattoos.
You'll find him in BG2 outside the thieves' guild, to the south under the shady courtyard.
You'll find him in Black Pits 2, away from the merchants' circle.
You'll find it in IWDEE, next to Coulon's forge in Kuldahar.

These tattoos are for single use only and are used like a tome: one tattoo = one ability or power.

They're expensive, but they're powerful. I know you like this.

An optional component halves the price to make them more affordables.

A second optional component (for IWDEE only) reduces tattoo prices by a further 20% (because the economy of IWDEE is not the same as that of BG2EE).

List of available tattoos:
Of Enhancement: normal or superior, it's one or the other, not both.
Tattoo of protection			+1 AC		25K
Tattoo of superior protection	+2 AC		50K
Tattoo of precision				+1 THAC0	25K
Tattoo of supreme precision		+3 THAC0, +1 to Critical Hit chances	100K
Tattoo of resistance			+1 saves								25K
Tattoo of superior resistance	+3 saves								50K
Tattoo of endurance				+3 maximum hit points					25K					
Tattoo of superior endurance	+9 maximum hit points					50K
Tattoo of specialisation		+1 damage on all attacks				25K
Tattoo of supreme specialisation+3 damage on all attacks, +3 THAC0		200K
Tattoo of the deceitful			+1 backstab multiplier					25K
Tattoo of the lucky devil		Luck +1									50K
Tattoo of the three treasures	+5% maximum hit points, +5% xp gained, +5% resistances	200K

Of Characteristic: normal or superior, it's one or the other, not both. (Exception: the Tattoo of transcendance is cumulative)
Tattoo of power					+1 STR		25K
Tattoo of superior power		+2 STR		50K	
Tattoo of action				+1 DEX		25K	
Tattoo of superior action		+2 DEX		50K	
Tattoo of health				+1 CON		25K
Tattoo of superior health		+2 CON		50K	
Tattoo of spirit				+1 WIS		25K
Tattoo of soul					+2 WIS		50K	
Tattoo of shrewdness			+1 INT		25K
Tattoo of revelation			+2 INT		50K	
Tattoo of presence				+1 CHA		25K
Tattoo of superior presence		+2 CHA		50K	
Tattoo of transcendance			+1 to all characteristics	200K

Of Class: normal or superior, it's one or the other, not both, and it's class reserved.
Tattoo of warrior				+1 STR, +1 AC, +3 maximum hit points														75K
Tattoo of supreme warrior		+3 STR, +3 AC, +9 maximum hit points														300K
Tattoo of wizard				+1 INT, +1 spell from levels 1 to 3, -1 casting time (non-EE) / damage +10% (EE)			75K
Tattoo of archimage				+3 INT, +1 spell from levels 1 to 9, -3 casting time (non-EE) / damage +30% (EE)			300K
Tattoo of thief					+1 DEX, +10 to all thief skills																75K
Tattoo of master thief			+3 DEX, +30 to all thief skills, luck +1													300K
Tattoo of cleric				+1 WIS, +1 spell from levels 1 and 2, Turn Undead Level +2									75K
Tattoo of archicleric			+3 WIS, +1 spell from levels 1 to 7, Turn Undead Level +6, 1x/day Defensive Harmony (AC+4, 1 turn) 300K
Tattoo of druid					+1 WIS, +1 spell from levels 1 to 4,														75K
Tattoo of Archidruid			+3 WIS, +1 spell from levels 1 to 7, +1 levels 5 spell, 1x/day Call Woodland Beings			300K
Tattoo of the master of the Shi	+1 DEX, +1 CON, +1 WIS, +1 attack/round, +3 fist damage										300K
Tattoo of the forester			+1 STR,	+1 DEX, +1 WIS, +1/2 attack/round, +30% to stealth, 1x/day Conjure animals			300K
Tattoo of the master of masks	+1 DEX, +1 INT, +1 CHA, 1 spell from levels 1 to 7, Armored spellcasting, 1x/jour Tenser's Transformation	300K
Tattoo of the Heritage			+1 CON, +1 INT, +1 CHA, +1 spell from levels 1 to 9, -3 casting time						300K
Tattoo of the Paragon of Virtue	+1 STR, +1 CON, +1 WIS, +1 CHA, Chant +1, Aid +1, Bless +1 (Minimal wisdom 15)				360K

Tattoo of acceleration			1x/day Haste										60K
Tattoo of the vermin			1x/day Summon Insects								60K
Tattoo of the blades Master		1x/day Tenser deadly strikes (5 rounds)				60K
Tattoo of the master of bones	1x/day Hold Undead									60K
Tattoo of creepers				2x/day Slashing creepers (Entangle +1D2 slashing)	70K
Tattoo of the silver tongue		+2 CHA, 1x/day Friend								70K
Tattoo of the broken lock		2x/day Knock										80K
Tattoo of the restless			1x/day Animate Dead									100K
Tattoo of life after death		1x/day Raise dead									100K
Tattoo of the traveler			Movement +2, 1x/day Dimension Door					100K

Of Creatures: it's one and only one, no other.
Tattoo of the Succubus			+1 CHA, +5% Magic Resistance, 1x/day Charm Person, 1x/day Draining Touch (1 level)	160K
Tattoo of the Minotaur			+1 STR, 1x/day Maze																	180K
Tattoo of the Nymph				+2 CHA, 1x/day Nature's Beauty														200K
Tattoo of the Medusa			1x/day Flesh to Stone, 1x/day Poison												200K
Tattoo of the Troll				+1 STR,	+1 CON, Immunity to fear, Regeneration 1/round								200K
Tattoo of the Modron			+1 INT, +1 WIS, Immune to Hold and Charm, 1x/day True Sight							240K
Tattoo of the Master brain		1x/day Feeblemind, 1x/day Power Word, Stun											240K
Tattoo of the Devil				+1 STR, +10% Magic Resistance, +50% Fire Resistance, +1 attack/round (Evil only)	260K

Of Outer Planes: it's one and only one, no other.
Tattoo of the Abyss				1x/day Summon Fiend												160K
Tattoo of Carceri				1x/day Imprisonment (save -4, MR)								180K
Tattoo of Baator				1x/day Gate														180K
Tattoo of Mount Celestia		1x/day Summon Deva (Loyal Good Only)							180K
Tattoo of Gehenna				1x/day Volcanic Rain (Fire, cold, acid 9D6 no save nor MR)		180K
Tattoo of the Gray Waste		Immune to Color Spells, 2x/day Emotion: Hopelssness (save -4)	200K
Tattoo of the Pandemonium		2x/day Chaos													200K
Tattoo of Mechanus				1x/day True Sight, 1x/day Chaotic Commands (personal)			200K
Tattoo of Bytopia						 1x/day Protection From Evil 10 foot, 1x/day Conjure Animals			200K
Tattoo of the elemental plane of earth	 1x/day Conjure Earth Elemental, 1x/day Stoneskin						200K
Tattoo of Arborea						 2x/day Barbarian Rage, 1x/day Call Woodland Beings						200K
Tattoo of the Positive energy plane		 1x/day Regenerate, 1x/day Negative Plane protection (2 turns)			220K
Tattoo of the Outlands					 1x/day Protection of the rings (blocks level 7 to 9 spells)			240K
Tattoo of Limbo							 +20 on Wild Surge Table, 1x/day Entropic zone, 1x/day Phantom Blade	260K
Tattoo of the elemental plane of air	 1x/day Conjure Air Archomental, 1x/day Chain Lightning					280K
Tattoo of the quasiele plane of vacuum	 2x/day Disintegrate													280K
Tattoo of the quasiele plane of radiance 1x/day Primatic Spray (save -4), 1x/day Sunray							300K
Tattoo of Acheron						 1x/day Transmute flesh to stone, 1x/day Conjure Elite orc troop		300K