Mind Flayers: DnD 5e Monster Guide

Guaranteed to blow your mind!

Mind Flayers (or Illithids) are alien humanoids of a greyish complexion with tentacles hanging over their mouths. While they aren’t physically powerful, they do have extremely powerful psychic abilities making them fearsome adversaries. They often use their psychic powers to subjugate “lesser” beings to their will seeing themselves as superior creatures.

Those unfortunate enough to be a victim of a mind flayer will usually have their brains consumed or their minds warped into mindless wretches with little hope of rescue. The illithid will often enslave people and societies in this manner, bending them to their will.

Mind Flayer Stats 5e

Mind flayers are formidable foes and a staple of many a campaign due to their unique psychic abilities and their ability to remove their victim’s brains, literally! There are a lot of variations of mind flayers but for these stats, we’ll stick with the basic garden variety:

  • Medium aberration, Lawful Evil
  • Armour Class: 15 (breastplate)
  • Hit Points: 71 (13d8 + 13)
  • Speed: 30ft

11 (+0)12 (+1)12 (+1)19 (+4)17 (+3)17 (+3)

Saving Throws: Int (+7), Wis (+6), Cha (+6)

Skills: Arcana (+7), Deception (+6), Insight (+6), Perception (+6), Persuasion (+6), Stealth (+4)

Senses: Darkvision 120ft., Passive Perception 16

Languages: Deep Speech, Undercommon, telepathy 120ft

Challenge: 7 (2,900 XP)

Magic Resistance: The mind flayer has advantage on saving throws against spells and other magical effects.

Innate Spellcasting (Psionics): The mind flayer’s innate spellcasting ability is Intelligence (spell save DC 15). It can innately cast the following spells, requiring no components:

At will: detect thoughts, levitate

1/day each: dominate monster, plane shift (self only) 


Tentacles: Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 15 (2d10 + 4) psychic damage. If the target is Medium or smaller, it is grappled (escape DC 15) and must succeed on a DC 15 Intelligence saving throw or be stunned until this grapple ends.

Extract Brain: Melee Weapon Attack: +9 to hit, reach 5 ft., one incapacitated humanoid grappled by the mind flayer. Hit: The target takes 55 (10d10) piercing damage. If this damage reduces the target to 0 hit points, the mind flayer kills the target by extracting and devouring its brain.

Mind Blast (Recharge 5-6): The mind flayer magically emits psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 15 Intelligence saving throw or take 22 (4d8 + 4) psychic damage and be stunned for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. This psychic blast can be absolutely devastating to a party in combat. It’s important to note that a stunned victim automatically fails strength and dexterity saving throws.

Mind Flayer physiology


Mind flayers don’t reproduce in the same way as most humanoids. Instead, they lay eggs from which are born tadpole-like offspring. The mind flayers will then take an inert humanoid and insert the offspring into the person’s cranium. For about a week, the offspring will slowly devour the victim’s brain replacing it with its own. The victim will also begin to change physiologically, developing increasingly illithid attributes until all that is left is a mind flayer. Sometimes, some vague memories of the mind flayer’s former life will emerge, but these rarely affect its personality or its desire to feed on the brains of others. This process is known as ceremorphosis.

The Elder Brain

Mind flayers use telepathy to communicate with each other but rather than operating as individuals, they instead operate more like a hive collective with an Elder Brain at the centre. The Elder Brain is a hugely powerful entity that exerts dominance over the mind flayers within its colony demanding absolute obedience. Mind flayers within a colony all know what each other sees and does with that information all feeding back to the Elder Brain who in turn directs the schemes of the mind flayers.

When a mind flayer becomes old or injured, the Elder Brain consumes them allowing them to live on in a state of immortality. It’s this collective knowledge that means the elder brain has a perfect recollection of the colony’s history, seeing itself as a saviour of the illithid race as well as a refugee from the threat of other monsters that would seek to destroy them.

An illithid that somehow strays away from an Elder Brain (the range of its psychic ability is 5 miles) might become free-willed. Perhaps the Elder Brain is destroyed or the mind flayer is captured, however it happens, the mind flayer has many enemies and will likely seek refuge by creating its own colony of subservient creatures for protection.

Occasionally, when a mind flayer is born, if it is particularly powerful and intelligent, then it will become an ulitharid. An ulitharid is in the early stages of becoming an elder brain and will strike out on its own taking half a colony with it to establish itself at least 100 miles from the old colony. While elder brains resent this weakening of their own colony, they also know that the only way to rebuild the illithid empire is to spread out and expand their influence.

Mind Flayer Speech

Typically, mind flayers communicate psychically, this being their natural form of speech. Even when speaking to “lesser” creatures, mind flayers will tend to use telepathy to communicate. Occassionally, a mind flayer might use verbal communication to speak. It will do so by putting a tentacle down its throat and bending it back on itself to act like a tongue. This is very uncomfortable so they tend not to use this method often.

Mind Flayer Variants

As mentioned, there are a wide array of different types of mind flayers from the standard, sully grown variety, to the hive mind of the elder brain to the tadpole that’s replace the brains of humanoids to transform into mind flayers. We’ve detailed all the mind flayer variants below:

Mind flayer

The standard form of a mind flayer that has undergone ceremorphosis of a humanoid. Such creatures are still formidable enemies capable of overpowering most with their psionic abilities.

Mind flayer arcanist

Some mind flayers supplement their psionic abilities with spells as some kind of mind flayer wizard. Such mind flayers are usually shunned as deviants by most other mind flayers.

Alhoon (illithilich)

Much like mind flayer arcanists, alhoons are mind flayers that have taken a pursuit of spellcasting, but in the case of the alhoon, these mind flayers have also attained immortality by becoming a lich.


Occasionally, a mind flayer will become so powerful that it is capable of transforming itself into an elder brain and starting a colony of it’s own. Prior to this transformation, such mind flayers are known as ulitharids.

Elder brain

Elder brains are the hive minds of a mind flayer colony and rule over the colony by the use of its powerful telepathic abilities. Such beings were once ordinary mind flayers themselves, but have become powerful enough to transform into an elder brain.


A neothelid is the result of abandoned mind flayer tadpoles that have had to survive by consuming one another until only one has survived. This creature has grown into a gigantic worm like creature that is terrifying to all, including mind flayers.

Vampiric illithid

Vampiric illithids have been rarely created using experimentation when a mind flayer tadpole is infected with vampirism. When this tadpole undergoes ceremorphosis, it will become a vampiric mind flayer that both needs blood (or spinal fluid) and brains to survive. Such beings have been found in Bluetspur as an experiment to help cure the god-brain’s disease.

Brainstealer dragon

Brainstealer dragons occur when ceremorphosis occurs on a dragon. This is obviously a rare occurence due to the scarcity of dragons and also their incredible power.


If a beholder can be stunned for long enough, it can be brought into the briney pool of an elder brain and transformed into a mindwitness, a cross between a beholder and a mind flayer that is subservient to the hive of the elder brain that transformed it.


The result of a mind flayer tadpole enacting ceremorphosis on a svirfneblin gnome that has then been subjected to dangerous psionic rituals.

Nerve swimmer

A derivative of immature mind flayer tadpoles that are used as instruments of torture by illithids.


The result of ceremorphosis on lizardfolk. Such creatures are highly prized by mind flayers for their particular viciousness in combat.

Illithid History

Thousands of years ago, the illithid had a vast and powerful empire spread across the astral domains of the inner planes with travel occurring between planes on flying vessels known as nautiloids. This ability to expand throughout space allowed them to dominate hundreds of worlds and the inhabitants there.

The main victims of the mind flayer’s expansive empire were the gith, who were enslaved and provided physical labour for their alien masters. At some point though, the gith rose up against their masters. It’s unknown how the gith managed to overthrow their evil overlords, but what is known is that after hundreds of years of subjugation, the gith were able to overthrow the illithid in the space of a year, taking down their entire empire.

After the gith revolution, all that remained of the mind flayers were those that had gone to inhabit the material plane. They are constantly hunted by the two factions of gith that arose from the combat; the githyanki and the githzerai. To this day, the illithid remain in hiding, scheming for the opportunity to return their empire to its former glory.

Mind flayers are formidable foes for any D&D campaign. If you want to use them in your campaign, you can find out more about them and their stats in Volo’s Guide to Monsters.

Using mind flayers in an adventure

Mind flayers are not only classic enemies in D&D, they’re also unique monsters to throw at your players, combining psionic powers with some terrifying, brain eating activity. They can make a great single enemy for lower level adventurers or a terrifying hive for higher level adventurers. Whatever your approach, we’re here to help you out.

The main thing to remember about mind flayers is that they are kind of squishy for challenge rating 7 enemies with stats not too dissimilar to a wizard with 15AC and 71 hit points. This is fine if the mind flayer is facing lower level adventurers, but this is the main challenge for mind flayers; staying alive to do the damage they’re capable of.

A mind flayer’s tentacle attack is decent, but the real damage comes from extract brain which can only be used if you’ve performed a tentacle attack and managed to grapple the adventurer. Extract brain will do whopping 10d10 damage and if the mind flayer reduces their victim to 0 hit points, they will instantly die. This is terrifying, but requires 2 turns in close combat to accomplish and while the to hit and grapple rolls are pretty good, there’s a good chance a mind flayer up close and personal with a party will get hacked apart before it can extract its victim’s brain.

This is where minions come in. Mind flayers are notorious for taking over the minds of others and using them as minions, and this can be pretty much any creature, so feel free to throw whatever you want at your players to support your mind flayer. Fighters, wizards, monsters; mind flayers aren’t picky. These can be used to help the mind flayer to single out an individual enemy and focus its attacks on them.

Even with minion support, you’ll still want to be wary of ranged attacks and spellcasters. Spellcasters can certainly cause problems with damage spells, Mind flayers have decent saving throws for wisdom, intelligence and charisma, but are much more vulnerable to damage spells including area of effect spells with only an average dexterity.

If you do need to manage the crowd a bit, mind flayers do have access to an ability called mind blast which allows the mind flayer to damage and potentially stun enemies in a large, 60ft cone area. It also has the spells dominate monster and plane shift if it needs to make a quick escape.

Beyond the standard mind flayer is an array of other mind flayer types you can bring in to add flavour and new tactics into the mix. Mind flayer arcanists and alhoons will add a big dose of spellcasting into the mix. Ulitharids are also tougher versions of mind flayers with a few extra psionic abilities in their repertoire. If you want something a little more savage and robust, you might also want to add in a vampiric illithid.

Published by DM Ben

Ben is an experienced dungeon master and player who's been immersed in the D&D universe since he was a teenager over 20 years ago. When he's not writing for Dungeon Mister, Ben loves creating fiendish puzzles and devious dungeons for his players. He's an especially big fan of the Ravenloft and Dragonlance settings.