What is this?

Mind Flayers appear in the majority of fifth edition publications. As a reader, getting your mind around all that content is quite challenging. To aid in that, this publication attempts to consolidate 5e's take on all things Mind Flayer related.

Sources

In several cases, newer official material supercedes prior material. This document uses the newest material (particularly with stat blocks); with the exception of paragraphical text -- Volo's Guide to Monsters text is used (Monsters of the Multiverse shorted much of the text to save space) where applicable. References are noted throughout this document as superscripts and include:

• AiS. Spelljammer: Adventures in Space
• BGG. Bigby Presents: Glory of the Giants
• DMM. Waterdeep: Dungeon of the Mad Mage
• FTD. Fisban's Treasury of Dragons
• MM. Monster Manual
• MotM. Mordenkainen Presents: Monsters of the Multiverse
• MToF. Mordenkainen's Tome of Foes
• RotF. Icewind Dale: Rime of the Frostmaiden
• TSO. Phandelver and Below: The Shattered Obelisk
• VGtM. Volo's Guide to Monsters
• VGtR. Vanrichten's Guide to Ravenloft

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Mind flayers, also known as illithids, are horrific, alien humanoids that lurk deep within the Underdark. Masters of psionic energy, they use their mental powers to dominate other creatures. The fortunate among their victims are slain, their brains devoured. The unlucky ones have their psyches warped, leaving them as mindless slaves with little hope of being rescued.

The Grand Design

The first priority of any mind flayer colony is to survive. The elder brain and its servants seek to remain hidden, typically deep within the earth, while harvesting enough intelligent humanoids to nourish themselves and allow for slow but steady growth.

Once a colony is secure, it focuses on the Grand Design — the mind flayers’ plan to rebuild their lost empire. The illithids know that reclaiming their rightful place in the world is possible only after the githzerai and githyanki have been eliminated and the remaining humanoids have been turned into docile slaves. To that end, each colony conducts research into the nature of the world and the creatures that inhabit it. The mind flayers examine all facets of reality, seeking any knowledge that could give them the edge they need to confront, defeat, and subjugate their enemies.

Every colony investigates a wide variety of topics and phenomena. A few members might focus on straightforward projects such as developing new uses for psionic power or how to breed savage creatures to serve as foot soldiers. Others pursue more theoretical subjects. A mind flayer might study musical tones, for example, in hopes of finding a way to manipulate the emotions of humanoids. Another might research the food humanoids eat to see if their diet or agricultural practices can be exploited. No line of inquiry is too esoteric if it might provide the next step in enacting the Grand Design.

Roleplaying a Mind Flayer

When you’re roleplaying a mind flayer, the following tables contain possible inspiration. They suggest characteristics that a mind flayer might possess.

Mind Flayer Bonds

Mind Flayer Flaws

Mind Flayer Names

Among mind flayers, thoughts aren’t communicated in language per se, but are instead transmitted telepathically as concepts and associations, which other humanoids interpret in their own language.

Telepathic communication with a mind flayer is frequently accompanied by a mental static that “sounds” to the receiver like an underlying sussuration peppered with guttural clicks. The intensity of this static increases when a mind flayer refers to itself, because with the saying of its name, the illithid is communicating far more information about itself than other humanoids can comprehend. The syllables that make up mind flayer names as expressed in other languages are thus weak approximations of the sound that others hear in their minds when illithids refer to themselves.

An illithid might adopt a name that is easier for minions and allies to speak or that makes it seem more fearsome to enemies, but each begins its life with a thought-name such as the examples in the Mind Flayer Names table, which are suitable for any campaign.

The Elder Brain

Mind flayers use telepathy to communicate with each other and with other creatures. Among their own kind, they form a network of minds. Each mind flayer is an individual node of the network, taking on specific tasks, sharing information, and so on. At the center of this network is the elder brain. The elder brain is the most powerful member of a mind flayer colony. Just as mind flayers treat thralls made from captured humanoids, an elder brain expects perfect obedience from the illithids that dwell in its colony.

If a single mind flayer in a colony sees or hears something, the elder brain and the rest of the illithids in the colony learn of it immediately. The colony relies on a collective memory, composed from the knowledge, experiences, and skills of all of its members and stored within the elder brain.

In some ways, a mind flayer colony is like a great library of lore stored within its members’ minds, with the elder brain as its librarian. Each individual illithid represents a category or subsection within the library. One mind flayer might specialize in biology, while another is an expert in defending the colony. Given that an individual mind flayer has a near-genius intellect, the extent of its knowledge is equivalent to the highest levels of scholarship attainable by humans.

There are limits to a colony’s reach. An illithid can be part of its colony’s network of minds only while it is within five miles of the elder brain. Beyond that distance, it is on its own. Mind flayers that venture away from the colony do so only under strict orders from the elder brain. Although such missions risk attracting unwanted attention, they can yield a treasure trove of knowledge and insights to be shared throughout the entire colony when a roaming mind flayer returns.

It is convenient for humanoids to understand a mind flayer colony by thinking of it as a single individual — the elder brain — directing a number of subservient, remote minds, which are the individual mind flayers. Perhaps at one time each mind flayer was independent, but now the elder brain is the only true power. The illithids know that their continued survival and their eventual return to power are possible only though perfect coordination and absolute obedience to the elder brain.

An elder brain is arrogant, scheming, and power hungry, yet quick to flee or beg for mercy in the face of a powerful foe. It has no conception of joy, sympathy, or charity, but is well acquainted with fear, anger, and curiosity. It is an intellect utterly incapable of empathy or concern for creatures other than itself.

An elder brain has a perfect recollection of its race’s history. Consequently, it views itself as both a refugee and a victim, forced into hiding by barbaric monsters. An elder brain also sees itself as a savior of the mind flayer race and a living memorial that preserves the memories of the mind flayers’ prey. By its twisted logic, humanoids whose brains are devoured by the colony are rendered immortal, their memories preserved forever in the elder brain’s labyrinthine mind.

When a mind flayer grows old, becomes infirm, or is grievously injured, the elder brain absorbs it — another form of immortality, as the mind flayer’s mind dwells within the hive mind forever after.

An Elder Brain’s Lair

The lair of an elder brain always lies deep in the heart of a mind flayer colony. The creature dwells in a dimly glowing brine pool, filled with foul and brackish water infused with the elder brain’s vital fluids and with psionic energy. Lair Actions

When fighting inside its lair, an elder brain can use lair actions. On initiative count 20 (losing initiative ties), an elder brain can take one lair action to cause one of the following effects; the elder brain can’t use the same lair action two rounds in a row:

• Force Wall. The elder brain casts wall of force.
• Psionic Anchor. The elder brain targets one creature it can sense within 120 feet of it and anchors it by sheer force of will. The target must make a DC 18 Charisma saving throw. On a failed save, its speed is reduced to 0, and it can't teleport. It can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
• Psychic Inspiration. The elder brain targets one friendly creature it can sense within 120 feet of it. The target has a flash of inspiration and gains advantage on one attack roll, ability check, or saving throw it makes before the end of its next turn.

Regional Effects

The territory within 5 miles of an elder brain is altered by the creature’s psionic presence, which creates one or more of the following effects:

• Paranoia. Creatures within 5 miles of an elder brain feel as if they are being followed, even when they're not.
• Psychic Whispers. Any creature with which the elder brain has formed a psychic link hears faint, incomprehensible whispers in the deepest recesses of its mind. This psychic detritus consists of the elder brain's stray thoughts commingled with those of other creatures to which it is linked.
• Telepathic Eavesdropping. The elder brain can overhear any telepathic conversation within 5 miles of it. The creature that initiated the telepathic conversation makes a DC 18 Wisdom saving throw when telepathic contact is first established. If the save is successful, the creature is aware that something is eavesdropping. The nature of the eavesdropper isn't revealed.

If the elder brain dies, these effects immediately end.

Infected Elder Brain

Paranoid and obsessed, an elder brain can occasionally become manipulated by the Far Realm. These obsessions keep an elder brain from bringing its full telepathic might to bear, orchestrating defenses within the stronghold, or responding to anyone other than like-minded fanatics.

For all its weaknesses, the elder brain still perpetually tracks creatures within its stronghold with its Creature Sense ability. It likely knows what is coming and which denizens mean it harm. An infected elder brain will fight to the death.

Elder Brain Dragon

One of the few consolations available to those who must contend with a mind flayer colony is the limit of its reach, which spreads only as far as the influence of the colony’s elder brain. But this small solace withers away when a colony manages to capture a dragon. Teams of mind flayers bind the dragon, which is subject to a gruesome transformation as the elder brain latches onto the dragon’s back and digs its tentacles into the dragon’s brain. An elder brain dragon is the nightmarish result.

Using the mobility of the dragon’s body, the elder brain can now serve as a powerful general to illithid armies, free from the confines of its brine pool. The elder brain dragon becomes a psychic threat in addition to a physical one, its body rife with aberrant influence and pulsing with psionic power. Even the elder brain dragon’s breath weapon mutates during its transformation, becoming a stream of briny liquid

roiling with illithid tadpoles. These tadpoles can swiftly slay victims and transform them into mind flayers, allowing the elder brain dragon to grow its own roving colony.

Colonized Illithids

Variant: Mind Flayer Psion^VGTM

Mind flayers sometimes devote themselves to deeper study of psionic power, and many excel at using their innate psionic energy to duplicate the casting of spells. A mind flayer psion has the same statistics as a mind flayer, except that its challenge rating is 8 (3,900 XP) and it has the following trait:

Innate Spellcasting (Psionics). The mind flayer is a 10th-level spellcaster. Its innate spellcasting ability is Intelligence (spell save DC 15; +7 to hit with spell attacks). It can innately cast the following spells, requiring no components:

---

• At will: guidance, mage hand, vicious mockery, true strike
• 1st level (4 slots): charm person, command, comprehend languages, sanctuary
• 2nd level (3 slots): crown of madness, phantasmal force, see invisibility
• 3rd level (3 slots): clairvoyance, fear, meld into stone
• 4th level (3 slots): confusion, stone shape
• 5th level (2 slots): scrying, telekinesis

Mind Flayer Prophet

Some mind flayers dedicate their lives to channeling abstruse truths from beyond reality. This insight gives them preternatural senses and allows them to focus their innate psionic power.

Ulitharid

Very rarely, the process of ceremorphosis yields an ulitharid, a more powerful mind flayer that isn’t beholden to the elder brain’s whims. A tadpole from an elder brain’s brine pool transforms an individual into an ulitharid, a larger and more potent mind flayer that boasts six tentacles.

The appearance of an ulitharid causes a surge in the colony’s collective intelligence, creativity, and strength. As the ulitharid gains power by devouring brains and honing its psionic abilities, the colony becomes more aggressive, seeking to gather more and more thralls.

Eventually, if the colony grows to sufficient size, the ulitharid strikes out on its own. Half the mind flayers and thralls in the colony undertake a great migration, seeking a new lair at least 100 miles away from the old one. Once the ulitharid finds a suitable spot, its followers construct a new lair while it transforms into an elder brain.

Although a creature as arrogant and ambitious as an elder brain might resent an ulitharid’s rise, it understands that the mind flayers can’t rebuild their shattered empire without expanding their reach. It might resent its new rival, but it can take comfort that soon enough the ulitharid will strike out on its own and the colony will return to normal.

Master Minds. Illithids innately recognize that an ulitharid’s survival is more important than their own. An elder brain’s reaction to the rise of an ulitharid varies. In most colonies, the ulitharid becomes an elder brain’s most favored servant, invested with power and authority. In others, the elder brain perceives an ulitharid as a potential rival for power, and it manipulates or quashes the ulitharid’s ambitions accordingly.

Birth of a Colony. When an ulitharid finds sharing leadership with an elder brain to be insufferable, it breaks off from the colony, taking a group of mind flayers with it, and moves to another location to form a new colony. After the death of the ulitharid’s body, mind flayers take its brain and place it in a brine pool, where it grows into an elder brain over a few days. This process doesn’t work on the brain of an ulitharid that dies a natural death, as a brain that succumbs to old age is too decrepit to be used in the creation of an elder brain.

Extractor Staff. Each ulitharid carries a psionically enhanced staff made of black metal. When the ulitharid is ready to give up its life, it attaches the staff to the back of its head, and the staff cracks open its skull and peels it apart, enabling its brain to be extracted. The brain and the staff are then planted in the ulitharid’s corpse, causing it to dissolve into ichor. This psionically potent slime helps to fuel the transformation of the area into a brine pool that surrounds an embryonic elder brain.

Ceremorphs

Gnome Ceremorph

The gnome squidlings have a blind hunger for brains that often overrides their common sense. Beyond such base hunger, the gnome squidlings don't know what they want. They have the reasoning and emotional control of toddlers blended with the guile of bored housecats.

Renegade Illithids

Sometimes a mind flayer that’s away from its colony breaks free from the elder brain. Perhaps it ran into a situation where its bonds of obedience were broken, or perhaps the colony was destroyed while it was away. In such a case, the mind flayer becomes free-willed for as long as it avoids contact with an elder brain.

A renegade illithid remains fearful of gith attacks, and likely sets about creating a sort of colony of its own, the better to remain undetected. It gathers minions, establishes a lair, and makes defense of its territory a top priority. Unlike colonial mind flayers, rogue illithids develop a healthy respect for those not of their kind. They treat especially powerful creatures and individuals as equals, not adversaries, and seek to cooperate with them. A renegade mind flayer might become a trusted advisor or a powerful ally, so long as it is kept well fed. Any alliance it makes, however, collapses if the mind flayer falls under the sway of an elder brain once more.

Arcane Magic

Mind flayers consider arcane magic to be an abomination, a twisted cousin of psionic power that will be erased from the multiverse when the illithids’ empire rises again. Some sages speculate that this attitude arose among the mind flayers because magic played an important role in the rebellion of the gith.

In any case, a few renegade mind flayers do pursue arcane magic. Using some of the items or spells they discover, they can shield their minds as they aspire to break free of the elder brain’s control.

Eventually, a mind flayer thus separated from the hive turns to the path of lichdom. Just as the elder brain offers immortality to its faithful illithids, so does becoming a lich ensure life everlasting. The feeling of freedom that comes from this change is liberating, but the specter of death forever after colors the mind flayer’s actions. An undead mind flayer is hated and hunted by other illithids, but many are powerful enough to stand on their own against attackers.

Alhoons

Mind flayers that pursue arcane magic are exiled as deviants, and for them no everlasting communion with an elder brain is possible. The road to lichdom offers an alternative way to escape the permanency of death, but that path is long and fraught with barriers. Alhoons are mind flayers who have used a shortcut to attain a lichlike state.

Elder brains forbid mind flayers from pursuing magic power aside from psionics, but it isn’t an interdiction they must often enforce. Illithids brook no masters but members of their own kind, so it isn’t in their nature to bow to any god or otherworldly patron. However, wizardry remains a temptation. In the pages of a spellbook, an illithid sees a system to acquire authority. Through the writings of the wizard who penned it, the illithid perceives the workings of a highly intelligent mind. Most mind flayers who find a spellbook react with abhorrence or indifference, but for some, a spellbook is a gateway to a new way of thinking.

For a time, the study of such forbidden texts can be hidden from other illithids and even from an elder brain. Yet eventually, mind flayer arcanists determined to pursue wizardry must flee the colony for their own safety. Once they taste freedom from the colony, some prize their privacy, others seek to commune with similar minds, and still others seek to dominate a colony by elevating themselves to the position of leadership normally held by an elder brain. Regardless, all such arcanists face the same stark fact: when they die, they will not join the host of minds in the elder brain—deviant minds are never accepted as part of the collective. For them, death means oblivion.

Lichdom offers salvation and the prospect of being able to pursue knowledge indefinitely. Yet learning the secret of achieving lichdom requires an arcane spellcaster to be at the apex of power—a significant challenge for mind flayers, given the scarcity of available mentors and training.

Confronting this reality, a group of nine mind flayer arcanists used their arcane magic and psionics to weave a new truth. These nine called themselves the Alhoon, and those who follow in their footsteps are referred to by the same name.

Mind Flayer Lich

The path to true lichdom is something only the most powerful mind flayer mages can pursue, since it requires the ability to craft a phylactery and cast the imprisonment spell.

Mind Flayer Clairvoyant

In pursuit of reconstructing their lost empire, a few mind flayers have turned to their home place, the Far Realm, for answers. A mind flayer clairvoyant has peered into that realm's starless depths and been subsequently rewarded with extraordinary powers.

Instead of heeding an elder brain, a mind flayer clairvoyant listens to the whispers and whims of the voices of the Far Realm. In addition to feasting on brains, a mind flayer clairvoyant can summon tentacles that rip through the fabric of reality and distort the minds of enemies.

Mind Flayer Warlock

When cut off from an elderbrain, mind flayers have been known to seek sources of power from other beings, sometimes even through pacts with supernatural powers such as Ilvaash (discussed later in this document).

Divine Magic

Illithids acknowledge the existence of divine entities, but it is unusual for any but a deviant mind flayer to actively worship such a power. Since they are capable of planar travel, illithids don’t view the afterlife and the Outer Planes in the mythic way that most other races do. Illithids don’t believe they possess souls whose eternal fate is governed by the gods. Instead, when a mind flayer’s brain is returned to the elder brain to be consumed, the creature’s intelligence lives on. Only if an illithid’s brain isn’t retrieved after death would its consciousness be cast into oblivion.

Two divine entities have long been associated with mind flayers by the scholars of other races. These aren’t deities, but rather manifestations of ideal psionic and philosophical mental states that mind flayers revere. Illithids occasionally meditate on these ideals while performing physical movements meant to help them achieve the proper attitude — actions that have often been misinterpreted by observers as worship.

Maanzecorian. The entity/concept called Maanzecorian embodies a complete comprehension of knowledge. It is a state wherein memories, thoughts, and aptitudes are dredged up from one’s mind not one at a time as needed, but are all laid bare and brought to the fore at once. The perfect memories exhibited by aboleths have long fascinated mind flayers that emulate Maanzecorian, leading to frequent conflict between the two races.

Ilsensine. Ilsensine is a broader philosophical ideal than Maanzecorian, leading many sages to assume it must be the more important or more powerful of the two “gods.” Ilsensine represents not just mastery of one’s own mind but a psionic union between oneself and the realm of universal knowledge. Different elder brains have different interpretations of what this state consists of and how to achieve it. Elder brains and illithids that devote themselves to Ilsensine sometimes pursue ways to dominate gods of knowledge or even aspire to supplant those gods on the way to attaining the state of full incorporation into the universal consciousness.

Ilvaash

Ilvaash is a godlet in the Far Realms, who is determined to reestablish a mind flayer empire on the Material Plane. Ivaash wants the empire to stretch across Toril's surface. When Ilvaash desires direct action on the Material Plane it does so through a Refraction of Ilvaash.

Mind Flayer Thralls

Mind flayers never truly ally with any creatures. They either attempt to seize control of a population by subverting its leaders, or they use psionics to dominate a humanoid and turn it into a thrall.

Illithids sometimes infiltrate an Underdark tribe of humanoids and use their superstitions and traditions as tools to make them useful followers. A mind flayer might use its psionic ability to send visions to a humanoid shaman, causing it to proclaim the mind flayers as emissaries of the gods. With that ruse in place, the “gods” then dictate strict rules that cause some members of the tribe to be branded as heretics, to provide the pretense for occasionally seizing a humanoid and devouring its brain. After the colony depletes and demoralizes the population sufficiently, the illithids might move in en masse and attempt to turn the remaining followers into thralls.

The process of transforming a creature into a thrall requires the entire colony’s energy and attention, making it no small matter. Although it takes only one mind flayer to perform the process, any illithid not directly involved in the process is required to donate its psionic power to the effort while otherwise remaining inactive.

A thrall-to-be is first rendered docile through psionic means. Using a low-power version of its Mind Blast ability, the mind flayer bombards the victim with energy that washes through its synapses like acid, clearing away its former personality and leaving it a partially empty shell. This step takes 24 hours. Over the next 48 hours, the illithids rebuild the victim’s memories and personality, and the victim gains the skills and talents it needs to perform its intended function.

The process that creates a thrall changes almost everything about the victim. The creature retains its Hit Dice, hit points, racial traits (but not proficiencies granted by race), and all of its ability scores except for Intelligence. After the first stage of the process, the creature’s Intelligence is halved; when the second stage is over, its Intelligence score increases by 1d6.

To complete the process, the thrall receives a new set of proficiencies, a new alignment, and a new personality. Some colonies have learned how to salvage a victim’s psionic abilities during the process or how to implant psionic powers into their thralls. Also, some colonies know how to leave a victim’s persona intact while infusing it with a fanatical loyalty to the colony’s elder brain as well as telepathic power that allows the victim to communicate with its new masters as if it were a mind flayer. This sort of thrall makes a perfect spy, since most would never suspect its true nature.

A thrall can be restored to its former self through a combination of spells and ministration. The thrall must have regenerate, heal and greater restoration cast on it once per day for three consecutive days. The victim is restored to normal when the final round of spells is cast.

Mind flayers vastly prefer to use humanoids as thralls, since they have a good balance of physical attributes and proper anatomy. Animals, in contrast, require a lot of direct oversight and lack the ability to use tools to help maintain the colony. Among the variety of humanoids available to the illithids, they have some preferences and tendencies.

Kuo-toa

Illithids once used kuo-toa as slaves extensively, since they proved quite easy to control. In time, though, repeated exposure to the mind flayers’ psionic intrusions drove the kuo-toa mad. Nowadays, kuo-toa don’t make for good thralls because their insanity makes them difficult to control. Mind flayers consider kuo-toa brains a great treat, but they prefer to eat them raw, unsullied by psionic alteration. Thus, they tend to eat kuo-toa soon after capturing them, rather than attempting to keep them penned up or docile.

Quaggoths

Mind flayers find that the quaggoths’ innate, though rarely manifested, talent for psionics makes them excellent thralls. When possible, they manipulate a tribe’s thonot (a psionic shaman) into pledging allegiance to a colony. Quaggoths are naturally strong and quick, making them ideal shock troops without any additional modifications. The quaggoths’ chaotic tendencies eventually motivate most colonies to convert them into thralls or food, rather than relying on the quaggoth thonot to keep them under control.

Oblexes

By experimenting on the slimes, jellies, and puddings that infest the depths of the Underdark, mind flayers created a special breed of Ooze, the oblex-a slime capable of assaulting the minds of other creatures. These pools of jelly are cunning hunters that feed on thoughts and memories. The sharper the mind, the better the meal, so oblexes hunt targets more likely to be intelligent, such as wizards and other spellcasters. When suitable fare comes within reach, an oblex draws its body up to engulf its victim. As it withdraws, it plunders the creature's mind, leaving its prey befuddled and confused- or dead. When oblexes feed on thoughts, they can form weird copies of their prey to use as lures, which helps them harvest even more victims for their mind flayer masters.

Mind Flayer Monsters

Mind flayers hardly ever use non-humanoid creatures as thralls or develop other relationships with them. Most of them are either too big and strong to keep penned up for long or too limited in intellect to complete anything but the simplest tasks. In general, non-humanoids found in the company of mind flayers are those that the illithids have created or bred for specific purposes. A few types of these creatures warrant special mention.

Cranium Rats

Mind flayers create cranium rats by bombarding normal rats with psionic energy.

Evil Collectives. Cranium rats are no smarter than ordinary rats and behave as such. However, if enough cranium rats come together to form a swarm, they merge their minds into a single intelligence with the accumulated memories of all the swarm’s constituents. The rats become smarter as a result, and they retain their heightened intelligence for as long as the swarm persists. The swarm also awakens latent psionic abilities implanted within each cranium rat by its mind flayer creators, bestowing upon the swarm psionic powers similar to spells.

A rat separated from the swarm becomes an ordinary cranium rat with an Intelligence of 15. It loses 1 point of Intelligence each day that it remains separated from the swarm. Its Intelligence can’t drop below 4 and becomes 15 again if it rejoins the swarm or another one.

Telepathic Vermin. A single, low-intelligence cranium rat uses its natural telepathy to communicate hunger, fear, and other base emotions. A swarm of cranium rats communicating telepathically “speaks” as one creature, often referring to itself using the collective pronouns “we” and “us.”

Spies for an Elder Brain. Mind flayer colonies use cranium rats as spies. The rats invade surface communities and act as eyes and ears for the elder brain, transmitting their thoughts when they swarm and are within range of the elder brain’s telepathy.

Cranium rats occasionally spread beyond the elder brain’s range of influence. Whatever these rats do is of no concern to the elder brain, and the illithids can always make more if they so desire.

Encephalons

When an illithid colony lays its eggs dangerously close to a Far Realm rift, an egg sac has a chance to nutate into what is known as an encephalon cluster -- a ravenous, slimy, psionic, brain-shaped mass that spawns horrors called encephalon gemmules.

Encephalon Gemmule

Due to the influence of the Far Realm, the eggs within an encephalon cluster no longer hatch into illithid tadpoles. Instead, when one of an encephalon cluster's eggs reaches maturity, it is ejected from the mass as an encephalon gemmule.

When spawned, a gemmule appears as a misshapen, spindly legged, pyramid-shaped nugget of soft, fleshy matter. If left to its own devices, an encephalon gemmule grows into an enncephalon cluster in a matter of days, at which point it begins producing its own gemmules.

Grell Psychic

Lurking close to a mind flayer elder brain is known to infuse grells with minor psychic abilities.

Mind Flayer Nothic

Originally mind flayers, these creatures have been transformed by some unknown source suspected to be from the Far Realm.

Intellect Devourers

Almost every mind flayer colony creates intellect devourers and seeds the areas around its lair with a few to keep watch, slay intruders, and lure fresh victims to their doom.

An intellect devourer resembles a walking brain protected by a crusty covering and set on bestial clawed legs. This foul aberration feeds on the intelligence of sentient creatures, taking over a victim’s body on behalf of its mind flayer masters.

Illithid Creations. Mind flayers breed intellect devourers to serve as roaming hunters of the Underdark, creating an intellect devourer by taking the brain of a thrall and subjecting it to a horrible ritual. As it sprouts legs, the brain becomes an intelligent predator as twisted and evil as its masters.

Deadly Puppet Masters. An intellect devourer consumes a creature’s mind and memories, then turns the host body into a puppet under its control. An intellect devourer typically uses its puppet host to lure others into the domain of the mind flayers to be enthralled or consumed.

Intellect Snare

When the strange horrors of the Farm Realm rip at the minds of individuals, some of those wayward shreds of thought conglomerate to form an intellect snare. An intellect snare appears as a writhing ball of tentacles, echoing with the cacophonous sounds of every thought the snare has consumed.

Intellect snares are scavengers, often found scouring the aftermath of a mind flayer attack to feast on whatever hapless creatures are left behind. An intellect snare feeds by wrapping a creature in one of its tentacles and then siphoning shreds of thought, leaving behind a tattered mind in its wake.

Mindwitnesses

A mindwitness represents an exception to the typical mind flayer pattern of reproduction. If a colony succeeds in capturing and subduing a beholder, it can use a tadpole to convert the creature into a bizarre hybrid known as a mindwitness. A mindwitness is a sort of psychic hub, able to collect and amplify the illithids’ psionic power.

If the beholder can be stunned and brought safely to the brine pool of the elder brain, it can be converted through ceremorphosis into a mindwitness. The process of ceremorphosis transforms four of the beholder’s eyestalks into tentacles similar to those of a mind flayer, and alters some of the beholder’s eye rays.

Less intelligent than beholders and less liable to endanger the colony, mindwitnesses are psionically imprinted with devotion to the elder brain and submission to illithid commands, making them almost as obedient as intellect devourers.

Telepathic Hub. The primary function of a mindwitness is to improve telepathic communication in a mind flayer colony. A creature in telepathic communication with a mindwitness can converse telepathically through it to as many as seven other creatures the mindwitness can see, allowing the rapid spread of commands and other information.

Solitary Seekers. If separated from its illithid masters, a mindwitness seeks out other telepathic creatures to tell it what to do. Mindwitnesses have been known to ally with flumphs and telepathic planar beings such as demons, shifting their worldview and changing their alignment to match that of their new masters.

Neothelids

These horrors, hated by mind flayers, sometimes come into being when those ignorant of mind flayer lore destroy a colony. A neothelid arises when a tadpole pool is left untended. The tadpoles turn against each other, and the survivor grows to immense size. Comparable to purple worms, these behemoths devour everything in their path.

A slime-covered worm of immense size, a neothelid is the result of the mind flayer reproductive cycle gone horribly wrong. On rare occasions, an illithid colony collapses, typically after an external assault, and the elder brain is killed. When that happens, the colony’s tadpoles are suddenly freed from their fate. They no longer serve as food, and in turn are no longer fed by their caretakers. Driven by hunger, they turn to devouring one another. Only one tadpole survives out of the thousands in the colony’s pool, and it emerges as a neothelid.

Abhorrent to Illithids. Among the strongest taboos in illithid society is the idea of allowing a mature tadpole to survive without implanting it into a donor brain. Under normal circumstances, any tadpole that grows larger than a few inches in length is killed by the elder brain to be food for it or for less mature tadpoles. Any tadpole that survives beyond that state is perceived as a threat to the colony, and the mind flayers organize hunting parties to exterminate the abomination. Lacking enough intelligence to be detected by an elder brain’s power to sense thoughts, neothelids warrant such precautions.

Savage Behemoth. As a feral thing, a neothelid knows nothing beyond the predatory existence it has lived so far and struggles to comprehend its new psionic abilities. Neothelids prowl subterranean passages in search of more brains to sate their constant hunger, growing ever more vicious. These creatures can spray tissue-dissolving enzymes from their tentacle ducts, reducing victims to a puddle of slime and leaving only the pulsing brain unharmed. They have no knowledge of their link to illithids, so they’re just as likely to prey on mind flayers as on anything else.

Psychic Gray Ooze

A gray ooze that lives a long time can evolve to become more intelligent and develop limited psionic ability. Such occurrences are more common in gray oozes that live near psionic creatures such as mind flayers, suggesting that the ooze can sense and mimic psionic ability.

Vampiric Mind Flayer

When the mind flayers of Bluetspur (discussed in later sections) could find no cure for their overlord's affliction, their degenerating elder brain turned to radical methods to stave off dementia and death. The results were vampiric mind flayers, feral atrocities spawned from mind flayer tadpoles infected with vampirism. These specialized but flawed terrors serve a single purpose: to drain the cerebral fluids from sapient minds. After doing so, they return to the Elder Brain of Bluetspur, which liquefies them into its pool and releases their stolen essences amid a hormone brine. This grotesque balm stalls the elder brain's degeneration but is far from a cure.

Vampiric mind flayers are physically and mentally unstable beings. Ghoulish creatures, they let nothing stand between them and their existential imperatives. Although they possess the telepathic abilities of mind flayers, their brains aren't equipped to employ them. Instead, they bombard nearby creatures with a mental static of visceral visions. While these ravenous creatures are horrifying to behold, they unsettle none more than other mind flayers, which consider them abominations.

Enemies Everywhere

Elder brains seek stability and safety for their colonies, and a colony can remain in a relatively peaceful state for decades if it can evade discovery while it acquires food.

Two kinds of events can disrupt the tranquility of a colony: an invasion and the appearance of an ulitharid.

Mind Flayer Lairs

In the lair of a mind flayer colony, the safety and security of its residents is all-important. As a result, illithid lairs are always well hidden and well defended, almost always underground, and within easy reach of humanoids and their succulent brains.

No two lairs are the same, as the resident elder brain drives the form and function of each one. The lair shown in the accompanying map is typical and includes many elements found in every colony’s stronghold.

The illithids, with their ability to levitate, design major portions of their lairs so as to make movement as difficult as possible for ordinary two-legged creatures. In such locations, thralls must climb or use ropes to move from place to place.

Nautiloids

Mind flayers employ bizarre flying ships called nautiloids. Able to move through the Astral Plane, nautiloids can also transport mind flayers between the various worlds of the Material Plane.

A nautiloid looks like an enormous conch shell fitted with an exterior deck and a large mass of rubbery tentacles. Ages ago, when the mind flayers could fly through the worlds of the Material Plane without resistance, they used the nautiloid’s tentacles to scour the surface for interesting creatures to take back home for study or a feasting.

The most notable feature of a nautiloid is its ability to move directly from one world to another in the Material Plane. Normally, travelers must venture to Sigil, a city in the Outer Planes, and find a doorway leading to the specific world they seek. But mind flayers can use nautiloids to move between worlds without going through Sigil. By this means, they have been able to spread themselves out into almost every corner of the multiverse.

Nowadays, a nautiloid is an incredibly rare sight. A colony in possession of one takes great care to keep it hidden, taking to the sky only out of necessity. Word of a nautiloid seen soaring through the air travels quickly in almost every world and is likely to attract the attention of vengeful githyanki and githzerai. A gith hunting party counts a nautiloid as the greatest prize it can claim, above even an elder brain.

The illithids have lost the secret of manufacturing nautiloids, meaning that the loss of any vessel brings them one step closer to remaining trapped on the Material Plane.

Id Ascendant^RotFM

This nautiloid variant has the following features:

• Biological Construction. The ship is built of organic matter in addition to wood and iron. Walls, floors, and ceilings are reinforced with tough chitin.
• Ceilings. Ceilings are 20 feet high unless otherwise noted.
• Illumination. All areas in the ship are dimly lit by fleshy, flickering, bioluminescent orbs mounted to the walls or hanging from the ceiling.
• Interior Doors. Each interior door aboard the ship is a fleshy sphincter that opens when a creature that has telepathy approaches within 5 feet of it, then quickly closes behind the creature and its companions. A door must otherwise be pried or tickled open, which requires an action.
• Life Support. The life support system keeps the ship's interior temperature at 50 degrees Fahrenheit (10 degrees Celsius).

N8. Observation Deck

A pintle mount for a telescope is fastened near the exterior railing.

N9. Captain's Quarters

This domed chamber has a table. Behind the table is a five-foot-diameter crystal sphere mounted atop a stand. Five strange, glowing gizmos are attached to the chitinous walls seven feet above the floor. These devices look like the tips of metal wands held in pincer-claws.

The five gizmos on the walls fire beams of radiant energy whenever a non-illithid is in the room. At the start of each turn, each gizmo targets a random creature in the room (including mind flayers). The target must succeed on a DC 16 Dexterity saving throw or be struck by the gizmo's beam, taking 4 (ld8) radiant damage. Each gizmo is a Tiny object with AC 16, 3 hit points, and immunity to poison and psychic damage. A character can use an action to try to tear a gizmo from the wall, doing so with a successful DC 10 Strength check. Reducing a gizmo to 0 hit points or tearing it from the wall destroys it.

Crystal Sphere. The crystal sphere is a cryogenic stasis pod, identical to the ones in area N3 and similarly nonfunctional.

Bluetspur^VGtR

Domain of Alien Memories

• Darklord: The God-Brain of Bluetspur
• Genre: Cosmic horror
• Hallmarks: Alien abductions, otherworldly landscapes, untrustworthy memories, monstrous experimentation
• Mist Talismans: Dream journal, metallic implant, scrap of bizarre technology

Protean apocalypses scar the impossible vistas of Bluetspur, and none who witness them remember. This alien domain etches itself not upon the waking mind, but rather upon the body as inexplicable scars and on the psyche through nightmares.

Not all the Domains of Dread are drawn from worlds hospitable to life. Bluetspur's scale and impossible geometry induce instinctual anxiety. Gaseous tempests whirl upon the hooked peaks of gravity-defying mountains, oily spires twist in semi-organic contortions, caustic fumaroles yawn and snap shut hungrily, and above it all hangs a dying red orb. Little can survive this wasteland, which is why Bluetspur's masters dwell underground.

Beneath the alien surface, the mind flayers of Bluetspur drift through the howling darkness of their ancient metropolis-laboratory. Within this sprawling installation, the illithids' numbers are few and their tentacles twitch with undisguised urgency. They toil to prevent the unthinkable: their primordial leader, the God-Brain of Bluetspur, is dying. Through these end times, the mind flayers work desperately to reconcile their god's demented whims even as they struggle to delay its demise. To those ends, their tentacles slip through the Mists to drag unwitting souls back to Bluetspur for all manner of experiments. Many abductees are returned with only psychic scars, while others are never seen again. An unlucky few find themselves set upon strange routes leading back to the alien realm, arriving only to realize they've visited Bluetspur before.

The God-Brain

The scope of what mind flayers call history exists on a cosmic scale. Through ages of empire and conflict, the illithid elder brains indulged experiments without comparison or reference for lesser beings, explorations beyond the boundaries of time, reality, immortality, and the multiverse. Many failed-at least one catastrophically so.

To summarize an eon of atrocities, one elder brain's reality-bending research had an unexpected result, revealing to it a malignant truth for which existence was unprepared. Guided by this burgeoning revelation, the elder brain turned and preyed upon its peers, consuming their discoveries and their physical forms to fuel an impossible apotheosis. Ultimately, though, the weight of the elder brain's deeds caused its own physicality to rebel, giving rise to an alien disease that began devouring its fleshy form. Horrified by an affliction that infected only them, the other elder brains united and psionically expelled the diseased brain from existence.

Or so they thought.

From a place without time or reality, the Dark Powers plucked the dying elder brain and planted it upon a tormented world. Ever since, the God-Brain of Bluetspur has dreamed and desperately indulged ever more demented schemes as it seeks to save its own life and give action to a thought alien even to it.

Adventures in Bluetspur

While Bluetspur's otherworldly hazards and the mind flayers' defenses can challenge even the highest-level heroes, the domain's menace proves most pernicious when it intrudes on other domains. Taking inspiration from sci-fi horror and tales of alien abduction, adventures involving Bluetspur's mind flayers might begin anywhere with bad dreams or a stranger's impossible rantings. Over time, disappearances, inexplicable scars, subdermal implants, and unlocked memories might reveal the mind flayers' tentacles enwrap more than anyone thought possible. See "Return to Bluetspur" for details on running adventures featuring lost memories, or consider developing other plots using the Bluetspur Adventures table.

Return to Bluetspur

Bluetspur can be more chilling as a memory than as a new discovery. Use this section to create adventures that reveal impossible knowledge, hint at unremembered experiences, or take place as recollected adventures out of continuity with a campaign.

Mind Flayer Miscellany

Some mind flayer colonies have developed the ability to create or modify certain kinds of gear, imbuing them with psionic energy. Mind flayers craft magic items that only they or their thralls can use — a sensible security measure to keep enemies from turning the illithids’ own creations against them.

Psipods

A psipod is a magic device that connects the mind of an unconscious humanoid to the mind of an ulitharid. The psychic residue that coats each psipod is a byproduct of this connection. The residue is sticky and foul-smelling, but harmless. It dissolves after a few hours.

Any creature that enters a psipod's bronze cylinder must succeed on a DC 17 Constitution saving throw or fall unconscious, lulled into that state by a soothing psionic vibration that the ulitharid produces. A creature that succeeds on the saving throw must repeat it at the end of each of its turns unit it exits the cylinder.

While in a psipod, an unconscious creature finds itself drawn into a simulated reality created by the ulitharid (see the "Alterdeep" sidebar) and can survive in this state for the remainder of its natural life, its mind and body nourished by the psipod's psychic energy. If the psipod is shut down, or if the unconscious creature is removed from it, the creature can repeat the DC 17 Constitution saving throw at the end of each of its turns, waking on a success. The creature also awakens if it takes damage in the real world, but not if it takes damage in the simulation.

Damage, Death, and Healing. Creatures can be hurt, healed, and killed in the simulation just as they can be in the real world, and a character reduced to 0 hit points makes death saving throws as normal.

Any creature that joins the simulation by entering a psipod and dies in the simulation also dies for real from the shock, as though it had taken enough psychic dam age to instantly kill it. Creatures immune to psychic damage can't be killed by this kind of system shock and stabilize automatically inside the simulation.

A psipod shuts down if it is disabled or destroyed. To disable a psipod, a creature must disconnect three of the eight copper wires connecting it to the metal panels in the floor. The mind flayers' schematic pads identify which three wires to disconnect on each psipod. (The combination of wires varies from one psipod to another.) If wires are torn out at random, roll a d8 three times (rerolling duplicate results) to determine which three wires shut down that particular

psipod, then roll a d8 for each wire that is disconnected to see if it's one of the correct ones. Disconnecting a wrong wire triggers a magical surge that targets all creatures within 5 feet of the psipod except the one inside it. A targeted creature must make a DC 17 Wisdom saving throw, taking 22 (4d10) psychic damage on a failed save, or half as much damage on a successful one. A magical surge from one psipod has no effect on the others.

All the psipods shut down if the ulitharid dies or leaves the area. Each psipod is a Large object with AC 15, 50 hit points, and immunity to poison and psychic damage. A creature inside a psipod has total cover against attacks originating from outside the capsule.

Mind Flayer Augmentations

Some mind flayer colonies augment their thralls with nonmagical gear to make them more effective as lair guardians and bodyguards. Two examples of mind flayer augmentations are presented here.