This character uses elements of the Eberron Campaign Setting and the Fiend Folio, which is where the "cerebral hood" appears. However, all the rules for the hood are reproduced below, so you can use him in any setting.
Quietus is a bard who has been lured into the Cult of the Dragon Below, a religion which worships aberrations and their otherworldly masters. As a servant to the cult, he has become grafted to a Cerebral Hood which now rules his actions. Once just a man with a bad temper, Qietus has now become an effective assassin for the Cult. He wears a mask over his face, which conceals the leathery skin of the hood. With the hood on his face, Quietus can manage little more than a whisper, and he uses scraps of strangled poetry to cast his spells.
On a typical mission, Quietus will already have cat’s grace, disguise self and expeditious retreat on himself, leaving him with 3/2/2/1 spells remaining. He may have already placed the oil of flaming weapon on his rapier and resheathed it.
Tactics: Round 1—mirror image from Quietus while the cerebral hood uses mind blast. Round 2—Quietus casts slow and lines up a mind blast on those who are unaffected. Mind blast from the cerebral hood. Round 3—Quietus casts blur and moves to target. The cerebral hood mind blasts for the third time. Round 4 and following—The cerebral hood uses mind blast. If Quietus is threatened, he uses glitterdust on foes. Otherwise, coup de grace on target.
Quietus (male human bard 7): CR 8; HD 7d6+14; 39 hp; Init +2; Spd 60 ft (with expeditious retreat); AC 19 (+4 Dex, +5 armor); BAB +5; Atk +9 melee (1d6+2 plus 1d6 fire/18-20 +1 rapier), +9 ranged; SQ bardic music, bardic knowledge +7, cerebral hood, spells; AL CE; SV Fort +3, Ref +7, Will +3; Str 13, Dex 14 (18), Con 12, Int 10, Wis 8, Cha 16 (18).
Skills: Balance +6, Concentration +11, Diplomacy +6, Disguise +14, Hide +14, Intimidate +6, Jump +3, Move Silently +14, Perform (poetry) +14, Sleight of Hand +6, Tumble +14; Dodge, Mobility, Quick Draw, Weapon Finesse.
Bard Spells Known (cast 3/4/3/1 per day): 0—daze, light, mage hand, prestidigitation, read magic, summon instrument; 1—disguise self, expeditious retreat, feather fall, lesser confusion; 2—blur, cat’s grace, glitterdust, mirror image; 3—charm monster, slow.
Bardic Music: Quietus can use bardic music 7 times a day. He can countersong, fascinate, inspire courage, or make a suggestion.
Fascinate: Quietus can fascinate three creatures within 90 feet who can both see and hear him. The effect is resisted with a Will save, with Quietus’s Perform check setting the DC. Fascinate lasts for a maximum of 7 rounds.
Inspire Courage: Quietus can inspire courage in himself and allies by reciting poetry. This grants a +1 bonus to attacks and weapon damage rolls, as well as a +1 against fear and charm effects.
Suggestion: Quietus can use suggestion on any creature he has already fascinated. This effect is resisted by a Will save (DC 17) and does not use a bardic music effect.
Cerebral Hood: The hood has 9 hp and can be attacked (AC 18). It has Ego 15.
Mind Blast: So long as the cerebral hood is attached to Quietus, it can attack with a mind blast (su) in a 60 foot cone, stunning all targets for 1d4 rounds unless they succeed in a Will save (DC 17). Each mind blast inflicts 1 point of Int damage to Quietus. If the hood is not attached, the mind blast has a range of only 15 feet, the save DC drops to 13, and targets are stunned for only 1 round. Note that the hood is an independent creature and so can use its mind blast on rounds when Quietus takes his own actions.
Blindsight: So long as the cerebral hood is attached, Quietus has blindsight to 60 feet.
Telepathy: The cerebral hood can communicate to any creature within 100 feet, as long as that creature has a language.
Equipment: Cloak of charisma +2, wand of detect magic (25 charges), +1 rapier, +1 mithril shirt, oil of flaming weapon, 215 gp.