Illithid

Mind flayers, also known as illithids (pronounced: /ɪlˈlɪθɪdz/ il-LITH-idz, meaning "mind flayers" or "mind rulers" in Undercommon), were evil and sadistic aberrations, feared by sentient creatures on many worlds across the multiverse due to their powerful innate psionic abilities. Dwellers of deep Underdark areas, these alien humanoid-looking beings sought to expand their dominion over all other creatures, controlling their minds to use them as hopeless slaves and devouring their brains for sustenance.
Their natural psionic abilities also made mind flayers respected in the eyes of the drow, beholders, duergar, and other dominant races of the Underdark.

Basic Information

Genetics and Reproduction

Reproduction

Illithids were all sexless, without male or female biological sex, and once or twice in their life they would lay a clutch of eggs from which tadpoles hatched. The tadpoles were kept in the elder brain tank, where they were fed brains by caretakers and engaged in cannibalism for around ten years. The elder brain also fed exclusively on tadpoles. Tadpoles that survived to maturity were put through the ceremony of ceremorphosis, where each was implanted into a humanoid victim and devoured its brain, taking its place and merging with the body to transform it into a new illithid. Only some humanoid species were suitable hosts for illithid tadpoles.
The multiplication of mind flayer colonies happened when a tadpole, quite rarely, through ceremorphosis, created a more powerful form known as an ulitharid (meaning "noble devourer" in Undercommon), which was biologically bigger, stronger, and more powerful and cunning than regular mind flayers. They possessed six face tentacles instead of the regular four. Most notably, however, they were not controlled by the elder brain. The appearance of an ulitharid caused a burst of growth in both the colony's size and capabilities. Elder brains grudgingly accepted the appearance of a potential rival, because eventually the ulitharid broke off from the colony. When doing so, it took a few mind flayers with it and sought to establish a new colony in a distant location from the original. Eventually, the ulitharid transformed into a new elder brain.
If, for some reason, a mature tadpole did not undergo the process of ceremorphosis, it became a ravenous predatory creature known as an illithocyte or, if allowed to grow out of control, a neothelid. These creatures were considered abhorrent by the illithids and were mercilessly hunted.

Dietary Needs and Habits

Physiology

Illithids fed on the brains of sentient creatures (mainly humanoids). This was the only kind of nourishment that could sustain the mind flayer physiology, which required hormones, enzymes, and psychic energy that only brain tissue could provide. Feeding was a euphoric experience for a mind flayer, as it absorbed its victim's memories, personality, and fears. It was also viewed by them as the ultimate form of dominance over another creature.
A mind flayer needed to consume at least one intelligent brain per month in order to remain healthy. Malnourished mind flayers died after four months of brain deprivation. The psionic energy also left traces of the original prey's individuality on a mind flayer's sense of culture and aesthetics.

Additional Information

Social Structure

Society

Individual mind flayers were rarely found alone; rather, they were usually accompanied by two or more slaves mentally bound to them. Typical enslaved races found among mind flayers included grimlocks, ogres, quaggoths, and troglodytes. These enslaved species had in common the fact that they were not typically considered edible by the illithids.
Mind flayer communities (also called "colonies") typically ranged in size from two hundred to two thousand, and that was counting only the illithids. Each mind flayer in the community likely had at least two slaves to do its bidding. In these communities, the number of slaves often far outstripped the number of mind flayers. For example, the illithid city of Oryndoll had a total population of just under 24,000 as of 1372 DR, but mind flayers accounted for only about 4,300 of that number.
Mind flayer colonies operated as a single hive mind, with control centralized by an elder brain, a singular entity that exerted its telepathic control simultaneously over any mind flayer within a radius of five miles (eight kilometers). The elder brain was the heart of the community. Held in a pool of briny fluids, the elder brain consisted of all the brains of the dead mind flayers in the colony. It served as the center of the communication network, relaying information received from one mind flayer to the entire colony, storing all the collective knowledge of the colony, and issuing commands to individual mind flayers. The degree of control and organization exerted by the elder brain over a mind flayer community was so absolute that it was more convenient to think of a mind flayer colony as a single individual: the elder brain.
Although mind flayers willingly came together to achieve an end, they were always vying for more control in the community, but even then they were always beneath the elder brain. While individual mind flayers might have, at one time in their past, retained a certain degree of independent thought, after the collapse of the illithids' empires it was generally agreed upon by them that their survival required complete obedience to the elder brain.
Within the colonies, mind flayers organized themselves in ideological factions known as Creeds, which aligned with each particular illithid's abilities and philosophy. Representatives of the various Creeds organized themselves in "Elder Concords", which, under the auspices of the elder brain, coordinated the colony's various activities. In cases when multiple colonies pursued common objectives, a "Grand Elder Concord" was formed.
When problems arose or the mind flayers wished to discover some secret, they formed "inquisitions", a team of mind flayers, not unlike an adventuring party. Each mind flayer used its own talents and abilities to achieve the inquisition's goal. If a situation was too large for just an inquisition to handle, the mind flayer community put together a "cult". A cult was much larger than an inquisition and was spearheaded by two mind flayers who constantly vied for greater power within it. This type of mission, which put mind flayers temporarily out of reach from the elder brain, was regarded as dangerous but highly profitable if successful.
If a mind flayer remained out of reach from its elder brain, it was possible for it to reacquire its free will. These so-called renegade illithids could go on to establish their own colonies or, free from the elder brain's arrogant supremacy, even seek cooperation with other species. This new personality and any alliances that were made instantly vanished as soon as the renegade illithid fell back under control of an elder brain.

Facial characteristics

Mind flayers are humanoid in appearance but with an octopus-like, ridged head with four tentacles surrounding a lamprey-like mouth. They are warm-blooded amphibians, whose blood has a silvery-white color.
Their hands have long fingers and lacked the index finger, and their feet are two-toed and webbed. Mind flayer eyes are extremely sensitive to bright light, and they consider it painful, a characteristic that some Fede scholars attributed to the fact that their alien anatomy focused light in a strange way. Their vision is also more sensitive to the recognition of geometric patterns than that of other humanoids.
Mind flayers that are healthy from brain-rich diets excreted a kind of slimy mucous substance that coated their mauve skins.

Perception and Sensory Capabilities

Darkvision

Average Height

6 ft (1.8 m)

Average Weight

Human equivalent

Body Tint, Colouring and Marking

The colors of Illithid range from cool blues and greens to purples.