Elder Brain

The ultimate expression of illithid domination, an elder brain sprawls within a vat of viscous brine, touching the thoughts of creatures near and far. It scrawls upon the canvas of their minds, rewriting their thoughts and authoring their dreams.
Psychic Infiltrators. When an elder brain infiltrates a mind, it alters the creature's perception and deceives its senses, causing it to see, hear, touch, taste, or feel reality according to the elder brain's intent. From across great distances, it implants subconscious suggestions or subtly influences dreams to compel creatures toward a course of action that benefits its grand plan.
When its insidious suggestions fail to take hold, an elder brain asserts its dominance more directly. It seizes control of a resistant mind and controls the creature's body as it would a puppet. Against the rare, strong-willed stalwart that defies it or attacks it, an elder brain sends a blast of overwhelming psychic force to crush the upstart's mind, rendering the creature a thoughtless, drooling shell.

Basic Information

Dietary Needs and Habits

An elder brain sustains itself by consuming the brains of other creatures. When the mind flayer servants that guard and tend to an elder brain don't bring its meals directly to it, the elder brain reaches out with tendrils of thought, mentally compelling creatures to come to it so that it may feed upon them.
When a mind flayer perishes, the elder brain's servants feed the contents of its skull to their master, which absorbs the illithid's brain and all the knowledge and experience contained therein. In this way the elder brain continually increases its knowledge, uniting the thoughts and experiences of the illithid colony into a unified whole. Illithid conceive of this "oneness" as a sacred state in the same way that a worshiper of a human deity might view an eternal afterlife in the heavens-for an elder brain can evoke the persona of any illithid it has ever absorbed.

Additional Information

Social Structure

Each elder brain considers itself and its desires the most important things in the multiverse, the mind flayers in its colony nothing more than extensions of its will. But no two elder brains are alike, and each presides over its colony according to its own unique personality and storehouse of collected knowledge and experience. Some elder brains reign as domineering tyrants, while others serve more benignly as sages, counselors, and repositories of information and lore for the mind flayers that protect and nourish them.
The ambitions of an elder brain are always tempered by its relative immobility. Although its telepathic senses can reach for miles, moving anywhere is always a dangerous proposition. If forced outside its brine pool, an elder brain will swiftly expire, and transporting an elder brain in its pool through confining and tortuous subterranean tunnels frequently proves difficult or impossible.

Civilization and Culture

Major Language Groups and Dialects

Hive Mind. Non-illithids call this creature an elder brain because it acts as the central communication hub for an entire mind flayer colony just as a brain does for a living body. Linked to the elder brain, the colony acts like a single organism, acting in concert as if each illithid were the digit of a hand.

Related Ethnicities

• Illithid Empire residents

Elder Brain

Large aberration, lawful evil

Armor Class 10

Hit Points 210 20d10+100

Speed 5ft Swim: 10ft

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STR

15 +2

DEX

10 0

CON

20 +5

INT

21 +5

WIS

19 +4

CHA

24 +7

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Saving Throws Int +10, Wis +9, Cha +12

Skills Arcana +10, Deception +12, lnsight +14, Intimidation +12, Persuasion +12

Senses blindsight 120 ft., passive Perception 14

Languages telepathy 5 miles

Challenge 14

Creature Sense. The elder brain is aware of the presence of creatures within 5 miles of it that have an Intelligence score of 4 or higher. It knows the distance and direction to each creature, as well as each one's Intelligence score, but can't sense anything else about it. A creature protected by a mind blank spell, a nondetection spell, or similar magic can't be perceived in this manner.
Innate Spellcasting (Psionics). The elder brain's innate spellcasting ability is Intelligence (spell save DC 18). It can innately cast the following spells, requiring no components:
At will: detect thoughts, levitate
1/day each: dominate monster, geas (cast as an action), plane shift (self only), confusion, eyebite (through Psychic Link only), feeblemind, mass suggestion, project image, scrying, telekinesis
Legendary Resistance (3/Day). If the elder brain fails a saving throw, it can choose to succeed instead.
Magic Resistance. The elder brain has advantage on saving throws against spells and other magical effects.
Telepathic Hub. The elder brain can use its telepathy to initiate and maintain telepathic conversations with up to ten creatures at a time. The elder brain can let those creatures telepathically hear each other while connected in this way.

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Actions

Tentacle. Melee Weapon Attack: +7 to hit, reach 30 ft., one target. Hit: 20 (4d8 + 2) bludgeoning damage. If the target is a Huge or smaller creature, it is grappled (escape DC 15) and takes 9 (1d8 + 5) psychic damage at the start of each of its turns until the grapple ends. The elder brain can have up to four targets grappled at a time.
Mind Blast (Recharge 5-6). The elder brain magically emits psychic energy. Creatures of the elder brain's choice within 60 feet of it must succeed on a DC 18 Intelligence saving throw or take 60 (10d10 + 5) psychic damage and be stunned for 1 minute. A target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
Psychic Link. The elder brain targets one incapacitated or willing creature it can perceive with its Creature Sense trait and establishes a psychic link with that creature. Until the psychic link ends, the elder brain can perceive everything the target senses. The target becomes aware that something is linked to its mind once it is no longer incapacitated, and the elder brain can terminate the link at any time (no action required). The target can use an action on its turn to attempt to break the psychic link, doing so with a successful DC 18 Charisma saving throw. On a successful save, the target takes 32 (9d6) psychic damage and the link ends. The psychic link also ends if the target and the elder brain are more than 5 miles apart, with no consequences to the target. The elder brain can form psychic links with up to ten creatures at a time. It can cast all of its spells through a character it's formed a psychic link with, as if they were casting that spell.
Sense Thoughts. The elder brain targets a creature with which it has a psychic link. The elder brain gains insight into the target's reasoning, its emotional state, and thoughts that loom large in its mind (including things the target worries about, loves, or hates). The elder brain can also make a Charisma (Deception) check with advantage to deceive the target's mind into thinking it believes one idea or feels a particular emotion. The target contests this attempt with a Wisdom (Insight) check. If the elder brain succeeds, the mind believes the deception for 1 hour or until evidence of the lie is presented to the target.
Charm: The elder brain targets one humanoid it can see within 30 ft. of it. If the target can see the elder brain, the target must succeed on a DC 18 Intelligence saving throw against this magic or be charmed by the elder brain. The charmed target regards the elder brain as a trusted friend to be heeded and protected. Although the target isn't under the elder brain's control, it takes the elder brain's requests or actions in the most favorable way it can.
Each time the elder brain or the elder brain's companions do anything harmful to the target, it can repeat the saving throw, ending the effect on itself on a success. Otherwise, the effect lasts 24 hours or until the elder brain is destroyed, is on a different plane of existence than the target, or takes a bonus action to end the effect.
Enslave (3/day): The elder brain targets one creature it can see within 30 ft. of it. The target must succeed on a DC 18 Intelligence saving throw or be magically charmed by the elder brain until the elder brain dies or until it is on a different plane of existence from the target. The charmed target is under the elder brain's control and can't take reactions, and the elder brain and the target can communicate telepathically with each other over any distance.
Whenever the charmed target takes damage, the target can repeat the saving throw. On a success, the effect ends. No more than once every 24 hours, the target can also repeat the saving throw when it is at least 1 mile away from the elder brain.

Legendary Actions

The elder brain can take 3 legendary actions, choosing from the options below. It can take only one legendary action at a time and only at the end of another creature's turn. The elder brain regains spent legendary actions at the start of its turn.
Tentacle. The elder brain makes a tentacle attack.
Break Concentration. The elder brain targets a creature within 120 feet of it with which it has a psychic link. The elder brain breaks the creature's concentration on a spell it has cast. The creature also takes 3d4 psychic damage per level of the spell.
Psychic Pulse. The elder brain targets a creature within 120 feet of it with which it has a psychic link. Enemies of the elder brain within 10 feet of that creature take 32 (9d6) psychic damage.
Sever Psychic Link. The elder brain targets a creature within 120 feet of it with which it has a psychic link. The elder brain ends the link, causing the creature to have disadvantage on all ability checks, attack rolls, and saving throws until the end of the creature's next turn.

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:
• The elder brain casts wall of force.
• 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. If the target doesn't or can't use this benefit in that time, the inspiration is lost.
• 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 succeed on a DC 18 Charisma saving throw or be unable to leave its current space. It can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

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.

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:
• Creatures within 5 miles of an elder brain feel as if they are being followed, even when they are not.
• 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.
• The elder brain can overhear any telepathic conversation happening within 5 miles of it. The creature that initiated the telepathic conversation makes a DC 18 Wisdom (Insight) check when telepathic contact is first established. If the check succeeds, the creature is aware that something is eavesdropping on the conversation. The nature of the eavesdropper isn't revealed, and the elder brain can't participate in the telepathic conversation unless it has formed a psychic link with the creature that initiated it.
If the elder brain dies, these effects immediately end.