Mind flayer

Mind flayers, also known as illithids (, meaning "mind flayer" or "mind ruler" in Undercommon ), and sometimes referred to as ghaik by the githyanki, were sadistic aberrations feared by sentient creatures on many worlds across the multiverse due to their powerful psionic abilities. From their twisted lairs deep in the Underdark, these alien entities sought to expand their dominion over all other lifeforms, controlling their minds to use them as obedient thralls. They consumed their victims' very personality by extracting and devouring their brains while they were still alive.

Description
In terms of height, weight, and build, mind flayers were roughly comparable to thin humans, but it was at this point that any external comparison to humanoids ended. A mind flayer's body was, in fact, a gruesome mockery of the humanoid form. An illithid's flesh, was soft, supple, moist, and rubbery, resulting in an unmistakable texture easily distinguishable from any other creature by anyone familiar with it. Their skin ranged from mauve to greenish-violet in color. Mind flayers that were healthy from brain-rich diets excreted a thin film of limy, glistening mucus that kept in moisture and gave off a faint odor similar to onions, garlic, or even vanilla, although the smell was imperceptible from afar. Their blood had a silvery-white color.

An illithid's bulging, ridged, elongated head was reminiscent of an octopus, with a cluster of four flexible, unsegmented, extendable tentacles surrounding their mouths. The tentacles could range in length from, appearing shorter when an illithid was at rest. They writhed and undulated almost constantly and absent-mindedly while the illithid pondered or otherwise was not using them, and flexed in anticipation when sentient beings drew close. They were also incredibly dexterous, powerful, and could be fully controlled by the mind flayer to perform both fine and strength-based tasks.

In many apocryphal descriptions and diagrams, mind flayers were portrayed as having beaked mouths, possibly owing to their octopus-like heads. In reality, an illithid's mouth was more like that of a lamprey, with a circular, jawless orifice ringed by several rows of small, rasping teeth. The tentacles hung above and around their mouths and an oily slime constantly dripped out of their maws. Illithids did not possess exterior ears, rather hosting small, fleshy, ridged holes on both sides of their heads, nor did they have nostrils. Their eyes, sheltered by brow ridges, were uniformly pale and devoid of pupils in addition to being bloated and featureless, similar to those of blind cave fish.

Illithid hands were long, slender, and lacked an index finger, but were otherwise similar to those of normal humanoid creatures. The remaining fingers and opposable thumb were red to mauve in coloration, and their nails were thick and black. Though illithid nails seemed dangerous, they were actually blunt and composed of soft cartilage, and so had little hope of being effective weapons. Illithid feet were webbed and had only two toes, which were also nailed and could flex widely apart, as if to assist in swimming.

Illithids were known to dress in flowing and dramatic robes and cloaks. They were rarely seen without distinctively two-lobed boots, which concealed their webbed nature. They often wore high, flaring collars, dark hats, and various other pieces of ornamentation.

Personality
Mind flayers were tyrants, slavers, and planar voyagers. They viewed themselves as masterminds, controlling, harvesting, and twisting the potential of other creatures to further their evil and far-reaching goals. Although they cooperated to achieve a goal, they would back away at the first sign that something was not profitable to their self-serving interests.

Mind flayers were aggressive and elitist and would attempt to mentally dominate any non-slave, non-illithid that they met. However, despite their aggressiveness, illithids were ultimately a paranoid and fearful race. They were relentlessly hunted by the gith, so any mind flayer colony's first priority was concealment and survival.

Emotionally, a mind flayer appeared detached and calm, showing no signs of passion or loss of control. However, sometimes they showed great bouts of anger, which were difficult to identify as true emotions or mere display. The mind flayer mind knew only negative emotions, only finding fulfillment in the angry and sadistic act of consuming a brain. The closest to happiness any mind flayer could know was in its pride and in satisfying its curiosity.

Abilities
In spite of their lack of physical abilities, mind flayers were feared by all beings in the Underdark because of their great mental prowess. In addition to the small array of mind-affecting spells that every illithid had at its disposal to take control of its prey, they also frequently employed a powerful mind blast to affect a multitude of foes. The mind flayer's mind blast was a cone that stunned anyone caught within it.

Their abundant psionic powers allowed them to levitate at will, as well as to detect the thoughts of nearby creatures and to dominate or charm any kind of creature in their vicinity. Additionally, there were reports of mind flayers capable of controlling other by power of suggestion. They were also capable of teleporting themselves to other planes of existence by plane shifting.

Some illithids dedicated themselves to studying and honing their innate abilities. Known as illithid psions, they were capable of even more remarkable feats of psionic power, including telekinetic abilities akin to mage hand and telekinesis; further mental control abilities such as charm person, command, sanctuary, fear, crown of madness, phantasmal force, and confusion; and even divination abilities such as guidance, true strike, see invisibility, clairvoyance, and scrying.

Combat
Normally, a mind flayer would use its mind blast ability to stun a few foes and then drag them away to feed. Once it had its victims, it would attach all of its tentacles to the head of one of its prey. Then, the mind flayer sucked out the brain, instantly killing the creature, as long as it only had one head. Mind flayers mainly used their other spells to enslave their minions and keep them under total control, but they were also used on the battlefield.

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, 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 all mind flayers within a radius of. 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.

Goals
Due to their hatred of the sun, a few elder brains secretly worked toward the goal of extinguishing all of them, but most mind flayer communities focused on finding ways to comfortably operate under sunlight.

Language and Names
Illithids were capable of speaking Undercommon and Deep Speech but preferred telepathic communication. They also had a form of written language called Qualith, which consisted of patterns of four lines imbued with psionic energy, capable of conveying not only text but also the author's thoughts. Without the use of magic, it could only be read by other illithids.

Mind flayer names were strains of thoughts and images that identified them to other members of the race. Since these names were too complex to be pronounced or even expressed in words, other races of the Underdark adopted rough translations in Undercommon by usually combining descriptive words that conveyed the general idea of the mind flayers' original names in order to identify them. Sometimes, the illithids themselves chose to adopt pronounceable names for the benefit of their thralls or to instill fear in their enemies.

Magic
Mind flayers considered arcane magic an abomination. They viewed it as an inferior and corrupt form of psionic power that should disappear from the universe once the illithids regained control of it. It was speculated that this hatred was related to the role of magic in the gith rebellion.

Arcane magic was especially sought out by renegade illithids looking for ways to shield themselves from the elder brain's influence. Although most mind flayer arcanists were wizards, a few were also born with the gift of sorcery. Because a mind flayer sorcerer was naturally more intelligent than other mind flayers, it was better able to resist psionics. For the most part, an illithid with the gift of sorcery would use defensive spells such as greater invisibility and resist energy, as well as spells to further hinder enemies, such as ray of exhaustion and touch of idiocy.

Mind flayers were capable of channeling their psionic abilities to craft their own version of magic items. As a security measure, these items could only be used by the illithids or their thralls. They had a variety of abilities and applications, such as the survival mantle, which allowed the wearer to breathe in a vacuum, or mind carapace armors, which protected the wearer's mind as well as its body. They also had the ability to craft psionic seals, a type of brand that granted its wearer a variety of abilities.

Other items included mind blades, shields of far sight psychic swords, psychic reservoirs, resonance stones, tentacle extensions, gauntlets of Tyla'zhus, tessadyle robes and tendril rings of Ilsensine. Some illithids also experimented with symbiont creatures in order to create living carapaces of armor.



A rare and most treasured item in a mind flayer colony was a flying ship known as a nautiloid. Mind flayers once had a massive presence in space and commanded countless of these conch-shaped spelljammers. In fact, spacefaring mind flayers were sometimes quite different from their land-bound counterparts and acted more as traders than conquerors. However, incessant hunting by the gith and the fact that mind flayers lost the means to build them or acquire them from the arcane caused them to almost disappear.

Religion
As a race of planar travelers, mind flayers did not worship entities from the Outer Planes as deities and did not share the same mythical thoughts about the afterlife. Instead, an illithid's last desire upon death was to be rejoined with its elder brain, thus attaining a form of immortality by having its life experiences merged into the elder brain's consciousness. Elaborate funerary jars, also known as brain canisters, with the individual's biography inscribed in Qualith were commonly used by mind flayer colonies to preserve a dead mind flayer's brain until it was consumed by the elder brain.

However, mind flayers revered two manifestations of psionic ideals in a form resembling worship. These entities were not exactly deities but were revered as such and were capable of granting divine powers to their followers, even non-illithid ones.

The broader entity was known as Ilsensine, which embodied a mastery of one's own mind and a union with universal knowledge. Mind flayer colonies interpreted this concept in different ways. Some viewed it as a promise of power and domination to its followers, a feature that was also attractive to non-illithid followers. Others interpreted these objectives as attainable through dominance or replacement of the deities associated with knowledge.

The influence of Ilsensine was important in the conflict between mind flayers of Oryndoll and the duergar. In the time when they had invaded the shield dwarf kingdom of Shanatar and captured many shield dwarves, the mind flayers had no gods. However, when the dwarves began to stage uprisings and rebellions, the city was plunged into chaos. The only reason it did not fall to the duergar rebellions was because of the sudden appearance of the mind flayer god Ilsensine. Since Ilsensine's appearance, the mind flayers became deeply religious and began to develop formidable psionic powers. Ilsensine's favored proxy was Lugribossk.

A smaller sect of mind flayers revered another entity called Maanzecorian. It embodied a complete comprehension of knowledge and the simultaneous access to memory, thought, and aptitude. It was also viewed by the illithids as a keeper of secrets. Its essence was killed by Tenebrous, the undead shadow of the demon lord Orcus sometime in the mid-14 century DR, though this fact was unknown to most at the time. However, in the late 15 century DR, mind flayer colonies dedicated to Maanzecorian were again common.

Some mind flayers viewed the perfect memory of the aboleths as a manifestation of Maanzecorian, which led to several conflicts between them.

Art
Mind flayer art focused on intricate geometric patterns and tessellations that expressed powerful emotions when viewed by most illithids. They could also see the beauty in gold, silver, and other types of treasure.

Relationships
Their natural psionic abilities made mind flayers respected in the eyes of the drow, beholders, duergar, and other dominant races of the Underdark.

Biology


Mind flayers were both warm-blooded and amphibious.

Diet
The sustenance of mind flayers were the brains of other creatures, mainly those of humanoids. Only brain tissue provided the required combination of the three essential components needed to sustain the mind flayer physiology: hormones, enzymes, and psychic energy. Mind flayers also ate other foods, most of which contained the critical enzymes and hormones they needed, with internal organs being good sources and high on the illithid menu.

While certain essential biochemicals and hormones could only be found in brain matter, illithids ate brains moreso for the psychic quotient of sentient gray matter than the physical nutrients. The mind flayer nervous system was unique in that every nerve had a direct connection to the brain, meaning that a mind flayer's digestive system was an extension of its brain, and therefore, along with the rest of the body, cognitive and self-aware in a sense. It was this unique digestive system that allowed them to extract more than nourishment from their food.

Stray memories were acquired from a mind flayer's prey, which they shared with the other members of their colony. As a result of their parasitic nature, traces of the victim's individuality were also retained by a mind flayer. While this did nothing to hamper their intelligence, it did influence their sense of culture and aesthetic preferences, ranging from their desired modes of architecture to their senses of style and decoration. Two communities might focus on or neglect entire areas of design based on their diet.

Psionic energy was extracted from the brain by an illithid in the victim's last moments of activity. The psychic essence freed from brains was nourishing in a way far more efficient and potent than flesh could be alone, metaphysically reenergizing their metabolism so well that only one intelligent brain was needed per month for them to remain healthy. Without this minimum requirement met, a mind flayer would slowly suffer physical debilitation and grow so weak that they would die in four months. Ideally they would eat a brain a week so as not to feel deprived, but most mind flayers fell between the two and ate brains about once every two weeks.

It was common for illithids to supplement their diets with other sources, by snacking on the brains of certain creatures they considered to be delicacies. Still, without the minimum essential brainpower, a mind flayer would slowly waste away. It was possible, although extremely rare, for a mind flayer to restrict its feeding by only consuming the brains of sufficiently intelligent lifeforms. A few animals that demonstrated extraordinary intelligence, such as exceptional cats, dogs, or bears, for example, sometimes had the psychic quotient required to properly nourish a mind flayer.

Despite being capable of doing so, a mind flayer that limited itself to such a restricted diet was rare. Mind flayers savored the minds they consumed, and the brains of thinking beings were preferable to those of lesser lifeforms. Experiences and emotions were the part that made the meal truly fulfilling, and the intelligence and imagination of the victim were a key factor in how highly rated a brain was. Various other elements influenced the flavor of a brain: a sense of great self-importance gave brains a pleasing tanginess, those afflicted with demonic madness were more succulent than sane ones, and active, magic-filled, and experienced minds were among the tastiest of all.

For these reasons, mind flayers had preferences for specific types of brains. For example, free individuals were more satisfying than thralls, with the thrilling lives of adventurers ranking their brains highly. Troglodytes, meanwhile, were considered absolutely terrible, to be consumed only in matters of life and death. Since creatures like goblins and hobgoblins reached "ripeness" faster than other races, they sometimes became staple foods, but were only eaten as a matter of necessity due to their lacking brainpower and creativity. Also avoided as food were the thick-skinned beholders, those diseased with lycanthropy, practically brainless beings like mites, some with natural healing capabilities like ogre magi, and spiritual entities such as devils.

In the Underdark, the sense of grandeur felt by the derro made them favored foodstuff, while drow, deep dwarves, and deep halflings were also highly valued. In particular, duergar brains were considered delicacies. Kuo-toa were also a great treat, although only if eaten raw and untainted by psionic energy, meaning they were eaten immediately upon capture. The best hunting ground was the surface, where even creatures like goblins, hobgoblins, orcs, and ogres tasted better than their subterranean counterparts, and where the most prized humans, halflings, elves, and dwarves resided. Small humanoids such as kobolds or gnomes were more frequently hunted for food than made into thralls, as they gathered in large groups, were easily forced into line by stronger thralls, and were often easier to drive to terror or despair, which made their brains tastier.

Umber hulks and xorns were infrequently consumed for their exotic nature. The blindness of grimlocks also created an exotic taste, but they had scaled hides and a foul taste, in addition to having similar drawbacks to goblins and hobgoblins. Sprites, satyrs, nymphs, and similar fey beings were hard-to-obtain delicacies. Some mind flayers also had specific tastes or appetites that deviated from the norm: some enjoyed engendering positive emotions before feeding and some were picky eaters, only feasting if the victim was conscious and aware or only devouring the brains of specific species.

All exceptions, tendencies, and special conditions notwithstanding, the brains of a large majority of humanoids (bugbears, orcs, and humans) were interchangeable in taste. Beyond dietary necessity, illithids consumed brains because doing so was an enjoyable activity. Feeding was a euphoric experience for a mind flayer, as it absorbed its victim's memories, personality, and deepest fears. If they could afford to eat more than one in a month, or even several in one week, they might choose to do so, obtaining both the pleasurable sensation and a psychic boost. All species were mere cattle before the mind flayers, and to consume brains was their ultimate act of dominance over another creature.

Senses
Mind flayer eyes were extremely sensitive to bright light, and they considered it painful, a characteristic that some githyanki scholars attributed to the fact that their alien anatomy focused light in a strange way. In fact, their eyes were more sensitive to infravision than to visible light, so that the entirety of their visual acuity was through darkvision, and they could see two additional colors in the spectrum beyond the color red. However, their visual acuity decreased as ambient light increased, as their their white sclera became increasingly opaque. In total darkness or under starlight, a mind flayer could see clearly as far out as, but under direct sunlight that infravisual range decreased to just. Mind flayer vision was also more sensitive to the recognition of geometric patterns than that of other humanoids.

While it did not actually harm them, illithids absolutely despised sunlight, avoiding it at all costs. They required only the heat created by the geothermic processes of planets to survive. Most mind flayers could not imagine living in the sun without some form of protection. from the desiccating effect it had on their skins to the clouding of their vision, and the mere thought of being immersed in sunlight was as horrifying to them as drowning in blood would be to a human.

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.

Illithid Monsters
Mind flayers constantly experimented with transforming other creatures and implanting their tadpoles into different races, producing a large variety of thralls.

The process of ceremorphosis yielded a new mind flayer only if the tadpole was applied to certain compatible types of humanoids. Normally, attempting ceremorphosis on an incompatible creature resulted in death for both the host and the tadpole. However, illithid research showed that it was sometimes possible to perform ceremorphosis even on an incompatible host. Creatures that underwent successful ceremorphosis but did not produce mind flayers were referred to as ceremorphs, or "flayer-kin". Some known types of ceremorphs included:


 * Brainstealer dragon:
 * The result of implanting a tadpole in a captured dragon.


 * Gnome ceremorph:
 * The result of implanting a tadpole into a gnome; only viable by slightly warping the ceremorphosis process. If unsuccessful, the resulting creature was a gnome squidling.


 * Mindwitness:
 * The result of implanting a tadpole in a captured beholder.


 * Mozgriken:
 * The result of a tadpole being inserted into a deep gnome and then subjected to psychic surgery that channeled energy from the Shadowfell.


 * Tzakandi:
 * The result of a tadpole being inserted into lizardfolk.


 * Uchuulon:
 * The result of a chuul being implanted with a tadpole.


 * Urophion:
 * A roper that had survived the tadpole implantation process.

In addition to ceremorphosis, many illithid colonies experimented with altering creatures in a variety of ways to produce new monsters that could serve them. Most such experiments resulted in shapeless abominations, but a few were occasionally successful and produced viable servants. Some known illithid-created monsters included:


 * Brain golem:
 * A large humanoid-shaped construct made entirely of brain tissue. They sprouted from the elder brain to conduct specific tasks or as a defense measure.


 * Cranium rat:
 * Regular rats bombarded with psionic energy. They could form intelligent swarms that grew smarter as they accumulated experiences.


 * Intellect devourer:
 * Creatures created by subjecting a slave's brain to a ritual that caused it to sprout legs. They were employed as guards or as bait to lure outsiders into a colony. The larval form of an intellect devourer, known as an ustilagor, was considered a delicacy by mind flayers and was commonly found in Oryndoll.


 * Mind worm:
 * An aquatic monster that resembled a pale, smaller purple worm. They were capable of attacking creatures through any reflective surface, even across different planes.


 * Nerve swimmer:
 * A modification of an immature tadpole. Used by some mind flayer colonies such as Oryndoll as a torture instrument.


 * Nyraala golem:
 * A large partially-humanoid construct that did not require the tissue of the elder brain. They almost rivaled brain golems in power and were more numerous in known illithid cities.


 * Oblex:
 * The result of experimentation with oozes. They fed on their victims' memories and could assume their shapes and identities.

There were also creatures thought to have originated in the same world as illithids and related to them in the same way that animals were akin to humans. These creatures, known as illithidae, were sometimes found near mind flayer settlements. It was unknown whether they were naturally attracted by the colonies or if they had been domesticated by the mind flayers. Some sages believed that gas spores had been created by mind flayers as well.

If mind flayers became undead, their new forms were also alien and in many ways different from other undead creatures. Typical undead mind flayers included:


 * Alhoon:
 * A mind flayer who decided to follow the path of wizardry could achieve a lesser form of lichdom and become an undead creature known as an alhoon. It was also possible, although rare, for an extremely powerful mind flayer wizard to become a true lich, also known as an illithilich. These terrible beings were so rare that usually people did not make that distinction.


 * Vampiric illithid:
 * A feral undead illithid with vampiric powers. Its origin was unknown.

History
The illithid race was extremely old and predated recorded history, as ancient texts that did not mention younger races already mentioned illithids. The mind flayers themselves appeared not to have much knowledge of their eldritch origins.

Origins
Some sages theorized that mind flayers were aliens from an unimaginably distant future, who had come back in time to prevent their extinction from being brought upon by the end of the universe. By the use of a powerful spell, they sent their great spelljamming fleet back in time, arriving at different time periods in different crystal spheres and reestablishing their empires. This interpretation was consistent with the fact that aboleths, even with their perfect racial memories, did not remember the beginnings of the illithid race.

Others believed that, because of their advanced technology and ships, illithids were a cursed, inbred mutant offspring of humans from an ancient and distant crystal sphere known as Clusterspace, forced to live in the underground depths of their world, honing their mental skills and experimenting with psionic powers for ages until the hate for their oppressors caused them to seek vengeance and set out to conquer the universe.

Other scholars dismissed the origin myths of illithids as a mutant breed of humans, instead believing that they might have originated in the Far Realm, (referred to as the "Outside" in the Sargonne Prophecies,) or at least had been warped by it. A group of mind flayers who later reached the Far Realm on a nautiloid returned with drastically changed bodies, minds, and goals, worshiping an unknown entity referred to as Thoon.

Most origin myths agreed that, an untold number of millennia in their past, mind flayers were the most powerful race in the Inner Planes, commanding vast empires from the Astral and Ethereal planes that spanned multiple worlds, kept under control by their nautiloids. The Planetreader's Primer, a book of ancient lore allegedly published in Sigil, further stated that the vast mind flayer empire also threatened the boundaries of the Outer Planes, at some point even disturbing the Blood War.

At some point, the gith, their most prominent slave race, rebelled and brought down the entirety of the mind flayer empires in the Astral Plane in less than a year. The surviving mind flayer enclaves in the Material Plane were constantly and mercilessly hunted down by raiding parties from both the githyanki and githzerai factions, bringing the illithid race to the brink of extinction.

Recorded History
Sometime around, illithid refugees from the planet Glyth arrived on Toril and founded the city of Oryndoll in the Underdark.

In, the illithids from Oryndoll attacked eastern Shanatar, starting the twenty-year long Mindstalker Wars. The war ended with a retreat of the illithids, but they managed to capture and enslave the dwarves from Clan Duergar, who were experimented with during the following millennia and eventually became the duergar subrace. Around, the duergar slaves rebelled and broke free from the mind flayers, nearly destroying Oryndoll, which narrowly escaped destruction thanks to the appearance of an avatar of Ilsensine. The duergar subsequently founded several holds across the northern Underdark. In, the city of Oryndoll was attacked by the duergar as part of a series of attacks against all their enemies.

The mind flayers had the first contact with the Netherese in.

In, an army of illithids and lycanthrope slaves invaded and conquered the dwarven city of Gauntlgrym. The ruined city remained disputed by groups of aboleths, duergar, drow, and illithids until it was retaken by the Companions of the Hall in the late 15 century DR.

In, the town of Ch'Chitl was founded by an illithid cult seeking to establish a partnership with Skullport. The city's elder brain planned to use the town as a foothold in a move to enslave Waterdeep. In, however, the city was attacked by githyanki, who mortally injured the elder brain and derailed their invasion plans. In, the city was ravaged by the Spellplague, which created horribly mutated mind flayers with extraordinary psionic abilities.

Sometime in the mid-13 century DR, the illithids managed to reestablish their domain on Glyth, from where they conducted selective breeding experiments with oortlings. Around that same time, there was also an illithid colony in a free-standing object in Realmspace known as the Skull of the Void, in which they performed breeding experiments on beholders. Decades of consumption of the beholders' brains conferred to the illithid inhabitants and their descendants the ability to levitate. Sometime in the late 14 century DR, Glyth was laid to waste by the elder evil known as Atropus, who had been concealed in one of the planet's rings. However, by the next century, mind flayer colonies were again present on the planet.

During the Time of Troubles, Oryndoll was once again visited by an avatar of Ilsensine, an event that ushered a large expansion in the city's creeds. Shortly afterward, members of the Loretaker Creed traveled to the Caverns of Thought in search of Ilsensine but returned as firm followers of Thoon.

In the late 15 century DR, mind flayers had lost the knowledge of how to construct their plane-crossing nautiloid vessels. Since the illithids knew that the end of the nautiloids would mean their permanent exile in the Material Plane, a few colonies were dedicated to rediscovering the secrets of nautiloid construction.

Notable Mind Flayers

 * Galuum, an inhabitant of the Ryxyg enclave sent to enslave duergar in the Waydown in the late 15 century DR.
 * Gideos, leader of the Bloodrovers, a pirate band from Avernus.
 * Grazilaxx, a member of the Society of Brilliance.
 * Methil El-Viddenvelp, chief advisor to House Baenre on matters concerning the borders of Menzoberranzan.
 * Captain N'ghathrod of the Scavenger, a space pirate native to Glyth.
 * Nihiloor, a mind flayer who worked for the Xanathar's Thieves' Guild. It was fond of creating intellect devourers and setting them loose throughout Waterdeep.
 * Vestress, a rogue illithid who served the Kraken Society as Regent of Ascarle.
 * Yharaskrik, a mind flayer involved in the destruction of Crenshinibon in 1366 DR.
 * Xetzirbor, an inhabitant of the Cyrog enclave who journeyed to Gravenhollow to save the city's elder brain from death in the late 15 century DR.

Appearances

 * Adventures
 * City of the Spider Queen • Out of the Abyss • Waterdeep: Dragon Heist • Waterdeep: Dungeon of the Mad Mage • Icewind Dale: Rime of the Frostmaiden
 * Baldur's Gate: Descent into Avernus
 * Novels
 * Homeland • Exile • Sojourn • Into the Void • The Radiant Dragon • Starless Night • Siege of Darkness • Elminster: The Making of a Mage • Tangled Webs • Finder's Bane • The Nether Scroll • Servant of the Shard • Windwalker • The Ghost King • The Companions • Night of the Hunter • Rise of the King
 * The Maelstrom's Eye • The Paladins • The Crimson Gold • The Orc King • Vengeance of the Iron Dwarf • Archmage
 * Comics
 * Infernal Tides
 * Video Games
 * Eye of the Beholder • Eye of the Beholder II: The Legend of Darkmoon • Spelljammer: Pirates of Realmspace • Menzoberranzan • Descent to Undermountain • Icewind Dale • Baldur's Gate II: Shadows of Amn • Baldur's Gate II: Throne of Bhaal • Neverwinter Nights: Hordes of the Underdark • Neverwinter Nights 2 • Neverwinter Nights 2: Mask of the Betrayer • Baldur's Gate: The Black Pits • Neverwinter • Sword Coast Legends • Baldur's Gate: Siege of Dragonspear • Neverwinter Nights: Tyrants of the Moonsea • Idle Champions of the Forgotten Realms • Baldur's Gate III
 * Neverwinter Nights: Darkness over Daggerford
 * Organized Play & Licensed Adventures
 * The Occupation of Szith Morcane • The Malady of Elventree • Writhing in the Dark
 * Gamebooks
 * To Catch a Thief
 * Board Games
 * Lords of Waterdeep: Scoundrels of Skullport • Tyrants of the Underdark: Aberrations and Undead • Waterdeep: Dungeon of the Mad Mage &bull; Dungeons & Dragons Dice Masters: Trouble in Waterdeep
 * Card Games
 * AD&D Trading Cards
 * Lords of Waterdeep: Scoundrels of Skullport • Tyrants of the Underdark: Aberrations and Undead • Waterdeep: Dungeon of the Mad Mage &bull; Dungeons & Dragons Dice Masters: Trouble in Waterdeep
 * Card Games
 * AD&D Trading Cards