Mind flayer

Mind Flayer
Illithids (commonly known as mind flayers) are monstrous humanoid aberrations with psionic powers. They live in the moist caverns and cities of the enormous Underdark. They believe themselves to be the dominant species of the multiverse (see Spelljammer), and use other intelligent creatures as thralls, slaves, and cattle.

http://upload.wikimedia.org/wikipedia/en/thumb/9/9b/Illithid.jpg/180px-Illithid.jpg

Illithid Abilities The iconic Illithid Mindflayer from Dungeons & Dragons.Illithids have four octopus-like tentacles around a beaked or lamprey-like mouth, and require the brains of sentient creatures as part of their diet. An illithid who snares a living creature in all four of its tentacles can extract and devour its living brain. One of the most feared powers is the dreaded Mind Blast, where the illithid emits a cone-shaped psionic shockwave to incapacitate any creature with its mind for a short amount of time. Illithids also have other psionic powers, generally telepathic in nature, although their exact effects have varied over editions. Other powers include a defensive psionic shield and powers of psionic domination for controlling the minds of others.

http://upload.wikimedia.org/wikipedia/en/thumb/7/7d/1136901782734_D50-Lockwood_Todd-Transitions_134.jpg/180px-1136901782734_D50-Lockwood_Todd-Transitions_134.jpg

Illithid Biology Illithids are hermaphroditic creatures who each spawn a mass of larvae twice in their life. The larvae resemble miniature illithid heads or four-tentacled tadpoles. Larvae are left to develop in the pool of the Elder Brain. The ones that survive are inserted into the brain of a sentient creature. A human gives best results. Upon being implanted, the larva then grows and consumes the host's brain, absorbing the host's physical form entirely and becoming sentient itself, a mature Illithid. This process is called Ceremorphosis. Illithids often experiment with non-human hosts, but ceremorphosis involving other creatures usually fails, killing both host and larva.

When an illithid undergoes ceremorphosis, it can occasionally take on some elements of the absorbed host creature's former mind, such as mannerisms. This typically manifests as a nervous habit and/or reaction, like nail-biting or tapping one's foot. An adult illithid has even been known to hum a tune that its host knew in life. Usually, when a mind flayer inherits a trait like this, it keeps it a closely guarded secret, because, were its peers to learn of it, the illithid in question would surely be killed. This is due to an illithid legend of a being called the "Adversary." The legend holds that, eventually, an illithid larva that undergoes ceremorphosis will take on the host's personality and memory in its entirety. This "Adversary" would, mind and soul, still be the host, but with all the inherent abilities of an illithid. Though fortunately for the illithids, due to the mechanics of ceremorphosis, total assimilation of the host's personality and memories is technically impossible.

Occasionally, ceremorphosis can partially fail. Sometimes the larva does not contain enough chemicals to complete the mutation, sometimes there is psionic interference. Whatever the reason, it has happened that ceremorphosis has ended after the internal restructuring, resulting in a human body with an illithid's brain, personality and digestive tract. These unfortunates must still consume brains, typically by cutting open heads (as they lack the requisite tentacles.) These beings are sent as spies to the surface, where they easily blend in with humans.

http://upload.wikimedia.org/wikipedia/en/thumb/6/66/Dungeon94_illithid.jpg/180px-Dungeon94_illithid.jpg

The illithid society also maintains a long-standing taboo. Every so often, a mind flayer community is attacked and its inhabitants must flee. This leaves the larvae unattended. Bereft of exterior nourishment, they begin to consume one another. The survivor will eventually leave the pool in search of food (i.e., brains). These unmorphed larvae are known as Neothelids. If the neothelid consumes an intelligent creature it will awaken to sentience and psionic abilities, while retaining its memories of savage survival. The existence of these beasts is a guarded secret among illithids, and it is considered impolite to speak of them.