Canon:Brain in a Jar

Brain in a Jar is an element of the Dungeons & Dragons role-playing game. In addition to being undead, it is, simply put, a brain in a jar of preservative fluid. The concept may have been influenced strongly by such sci-fi and horror as They Saved Hitler's Brain and Doctor Who: The Brain of Morbius. It was introduced in Libris Mortis, a D&D supplement book that dealt specifically with undead. It is a live brain in a grimy jar filled with preservation fluid with powerful psionic abilities.

Society/History
The brain in a jar is a masterpiece of preservation -- but where alchemical preservatives leave off, necromancy picks up. An animated brain in a jar is, in truth, an undead creature. Additionally, a brain in a jar possesses potent mental powers (psionics).

Merely removing the brain of a zombie or some other undead creature and storing it in alchemical preservatives is not enough to create an undead brain with psionic ability. The ritual of extraction, the spells of formulation, and the alchemical recipes of preservation are closely guarded secrets held by only a few master necromancers.

The creation of a brain in a jar is difficult and fraught with danger, because once its mental powers are fully developed, this undead creature is adept at controlling the thoughts and minds of other creatures, especially living creatures. It is not unknown for a brain in a jar to take control over the necromancer who created it.

A Brain in a Jar is usually neutral evil in alignment.

Combat
The Brain in a Jar uses mainly psionic abilities to do what its lack of moving parts would otherwise prevent: move itself, manipulate objects and the environment, and ward off attackers. Its main attack is Mind Thrust, an assault upon the mind of another creature. In addition to this, it can also drive mad anyone who magically or psionically detects it, and it can control and rebuke other undead.