Mind flayer

The Illithid, also called the Mind Flayer, is an evil and sadistic being, humanoid in appearance, but with a four-tentacled octopus-like head. These fearsome beings are feared throughout the Underdark for their telepathic abilities and usually are not without two or more slaves, mentally bound, to each individual Mind Flayer. Although they are cooperative in working together to achieve a goal, they will back away at the first sign that it is not something that will be self-profitable. They are capable of speaking Undercommon, but prefer telepathic communication and will attempt to mentally dominate any non-slave, non-Illithid they meet. Theorized to be aliens from the future, they come back in time to save their species from extinction. They feed on the brains of sentient creatures and are thus feared. Their natural psionic abilities also make them respected in the eyes of the Drow, Beholders and Duergar, the other dominant races of the Underdark.

Illithid Psionics
The Illithids are feared by all beings in the Underdark because of their great mental prowess. Every Illithid has a small array of mind-effecting spells to take control of their prey as well as a powerful Mind Blast to effect a multitude of foes. The Mind Flayer's Mind Blast is a sixty foot cone that stuns anyone caught within it unless they succeed a DC17 Will save. The Mind Flayer also can innately cast three mind-effecting spells: Charm Monster, Detect Thoughts, and Suggestion, with DC17, DC15 and DC16 respectively. Mind Flayers are also capable of casting Levitate and Plane Shift. Each of these spells are cast as if by an eighth level caster, and the saving throw DCs are based off the Illithids charisma score.

Normally, an Illithid will use its Mind Blast ability to stun a few foes and then drag them away to feed. Once it has its victims, it must perform a successful grapple check and attach all of its tentacles to the head of its victim. Then, the Illithid uses its Extract ability to suck out the brains of its victims, instantly killing the victim, as long as it only has one head. The Illithid uses its other spells mainly to enslave its minions and keep them under total control, as well as in the battle field.

Mind Flayer Sorcerers
Although most Illithid casters are Wizards, few are also born with gift of Sorcery. Because an Mind Flayer Sorcerer naturally has higher charisma scores than other Mind Flayers, all of its saves for its psionic abilities are 4 points higher. For the most part, an Illithid with the gift of Sorcery will use defensive spells such as Greater Invisiblity and Resist Energy as well as spells to further hinder enemies, such as Ray of Exhaustion and Touch of Idiocy.

A typical spell book for a ninth level Mind Flayer Sorcerer is as follows: Cantrips: Arcane Mark, Daze, Detect Magic, Disrupt Undead, Flare, Ghost Sound, Light, Read Magic - Six Spells Per Day

First Level Spells: Chill Touch, Mage Armor, Magic Missle, Ray of Enfeeblement, Shocking Grasp - Eight Spells Per Day

Second Level Spells: Minor Image, Resist Energy, See Invisibility, Touch of Idiocy - Eight Spells Per Day

Third Level Spells: Fly, Haste, Ray of Exhaustion - Eight Spells Per Day

Fourth Level Spells: Greater Invisibility, Stoneskin - Five Spells Per Day

Illithid Society
Illithid communities range in size from two hundred to two thousand, and that is counting only the Illithids. Each Illithid in the community likely has at least two slaves to do its bidding. In these communities, the number of slaves often far outstrips the number of Illithids. For example, the Illithid city of Oryndoll has a total population of 26,000, but Illithids only make up for 3,450 of that number. Any Illithid knows better than to probe the mind of the slave of another of their kind. When problems arise or the Illithids wish to discover some secret, they form Inquisitions. These Inquisitions are made up of a team of Illithids, not unlike an adventuring party - each Illithid gives their own talents and abilities to achieve the Inquisitions goal. If a situation is too large for just an Inquisition to handle, the Illithid community puts together a Cult. A Cult is much larger than an Inquisition and is spear-headed by two Illithids who constantly vie for greater power within the Cult than the other. Although Illithids willingly come together to achieve an end, they are always vieing for more control in the community, but even then they are always beneath the Elder Brain. The Elder Brain is the heart of the community. Held in a pool of briny fluids, the Elder Brain consists of all the brains of the dead Illithids in the community.

Illithid Religion
Mind Flayer religion was once non-existant. In the time when they had invaded the Shield Dwarf kingdom of Shanatar and captured many shield dwarves, there were no gods to the Mind Flayers. Originally, their plan was to create a supierior race of dwarves, skilled in both mechanics and psionics that would be loyal soley to the Mind Flayers. However, when the dwarves began to stage uprisings and rebellions, the city of Oryndoll, where the experimentation was occuring, was plunged into chaos. The only reason the city did not fall in the Duergar rebellions was because of the sudden appearance of the Mind Flayer god Ilsensine. Since Ilsensine's appearance, the Mind Flayers have become deeply religious and began to devolop the formidable psionic powers that the race now has.