The Complete Guide to Mind Flayers in D&D 5e (Update 2023)

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Complete Guide to Mind Flayers in D&D 5e

Mind Flayers or Illithids, by any other name, a tentacled, psionic horror with a taste for brains would be just as sneaky.

Mind Flayers used to be the most powerful creatures in the Inner Planes, but now they are almost extinct.

Those who are still alive have gone into dark, secret places to hide. There, they plan and pass the time as they get ready to get back on their feet and reclaim the glory they once had.

So, dear reader, get ready!

Today we take a closer look at one of the most iconic creatures in all of Dungeons & Dragons: the Mind Flayer.

Read on if you dare!



Mind Flayers are easy to spot because they have a head like an octopus, with white eyes and four tentacles that cover their mouth. The Illithid have a lot of control over these tentacles, and they can reach out as far as 4 feet.

The Mind Flayer grabs its prey with these tentacles and holds it tight while it bites into its head with its small, round, razor-sharp-toothed mouth.

Most of the time, the skin of these creatures is different shades of mauve, but some have a slight greenish tint. Most of the time, they are about the same height as most people and very thin.

Making People Think The slime that makes up Flayer’s body is very thin. This mucus shows that the animal is healthy and getting enough food.

Any Illithid you meet is likely to be dangerous, but one with little or no slime is likely to be very hungry…

Most Mind Flayers wear clothes that look like they belong in the Underdark when it comes to what they wear. They often wear deep black robes, skull decorations, and breastplates, which make them look even more dangerous.


Mind Flayers can talk, but most of the time they talk to each other through telepathy.

If the Mind Flayer wants to talk to more than one creature, activate a magic item with a command word, or cast a spell that needs verbal parts, it has to make up a way to talk. They do this by sliding one of their tentacles down their throat and using it like a tongue.

This is a disgusting show that makes everyone involved feel bad.

Mind Flayers can use telepathy, but they also often speak Undercommon and any other languages they may have learned.


Mind Flayers use Qualith, which is a kind of “written language.” But this doesn’t work like written languages in a way that anyone else would understand.

Instead, the Qualith inscriptions send the creator’s thoughts to the Mind Flayer when the tentacles of the Mind Flayer touch the inscription.

Inscriptions of Qualith are made on non-magical, non-living things like stone. Since these markings don’t change the material in any real way, they can stay hidden even when they are in plain sight.

The inscriptions are written in four-line stanzas that must be read all at once. Most creatures that aren’t Illithid can’t figure out what these patterns mean.

If someone touches a Qualith inscription, they might be able to get a short “transmission” of the author’s thoughts.

When trying to figure out what a Quality inscription says, a character could make an Intelligence check against a DC based on how hard it is to understand.

But be careful!

Failure could have any number of results ranging from a small headache to short-term (or even long-term) madness!

For those who are determined to translate a Quality inscription, the Comprehend Languages spell would give a reasonably accurate understanding of the inscription. There might be some minor differences, but the majority of it should be similar to what a Mind Flayer would learn from the inscription.


The life cycle of a Mind Flayer starts with a group of parasitic tadpoles that hatch in Illithid spawning pools.

A single batch can have up to a thousand eggs, but most of them won’t grow up. The Elder Brain of the Mind Flayer colony eats the vast majority of these tadpoles.

Those that don’t get eaten by the Elder Brain are put into the noses or ears of the humanoids who are being held captive by the colony. The tadpole burrows into the host’s head, where it feeds and grows until it has completely replaced the brain and attached itself to the brain stem.

This process, which turns the host into a Mind Flayer, is called “Ceremorphosis.”

The Lifecycle of a Mind FlayerIt takes a month for the eggs of a Mind Flayer to hatch, but it takes ten years for the tadpoles to grow up enough to be put into a host.

Once the Illithid has completely taken over the host’s body, it stays in the colony for the next twenty years to grow and learn. If a Mind Flayer lives its whole life cycle, it could live up to 135 years.

When a Mind Flayer dies, its brain is taken out and its body is put into the spawning pool to be eaten by the Elder Brain. All of the creature’s knowledge is taken in by the Elder Brain, so this is seen as a great honor by Mind Flayers.

In the same way, not being able to join the Elder Brain is seen as a punishment that is even worse than death.


While the brains of intelligent creatures are used to create more of their kind, Mind Flayers also rely on brains as a food source.

Mind Flayer colonies will commonly be just out of sight of other creatures. If the colony is too far away, they sacrifice having a reliable food source for security. Ideally, the colony is close enough to a settlement of humanoids that there is plenty of brains to feed on but also hidden well enough that they are able to remain largely unbothered.

While the brains that they eat give them some physical sustenance, they are primarily nourished by the psionic energy that is released in the brain’s final moments.

Most commonly, a Mind Flayer will stun its prey with a powerful blast of psychic energy. With the victim unable to move, slimy tentacles wrap around their head and pull them closer to the Illithid’s mouth.

The Mind Flayer’s mouth produces a powerful enzyme that is able to melt through the victim’s skull. Only the mucus that drips from the Illithid’s skin is able to counteract this enzyme.

With the skull weakened and the prey stunned, the Mind Flayer extracts their victim’s brain.

With its prey stunned, the Mind Flayer begins extracting the brain.


Because Mind Flayers take in this psionic energy, you can sometimes learn a lot about what they eat by looking at how they look.

A Mind Flayer that mostly eats Elf brains will care more about wearing fancy robes and acting in a “elegant” way than one that mostly eats human brains. If it eats a lot of Dwarves, it might have symbols on its chestplate that look like Dwarven runes or on jars that hold brains that haven’t been used yet.

On the other hand, a Mind Flayer that mostly eats things like Goblins or Grimlocks is not likely to have these kinds of priorities.

These lingering traits are subtle and only show up after a lot of brains have been eaten. Still, it gives the Mind Flayers an even creepier vibe than they already had!


The baseline for survival for a Mind Flayer is being able to eat one brain per month. This isn’t ideal, but it will be able to survive in such conditions.

Particularly healthy Mind Flayers eat one brain every two weeks. In colonies with access to a large food supply, they may be able to eat brains as often as once per week.

Mind Flayers can feed off of the slaves that they keep in their colonies, but are typically hesitant to do so if given a choice.

The slaves take time to mature and are often better used to further grow the colony once the tadpoles have matured. Furthermore, the brains of slaves don’t possess the same amount of psychic energy that the brains of surface-dwelling intelligent creatures have.


Everything that is known about Mind Flayers’ diet details their consumption of humanoid brains.

Mind Flayers are physically capable of eating animal brains, but doing so would give them little to no nourishment.

Because only a very small amount of the nourishment that a Mind Flayer receives from eating a brain is from the physical substance of that brain, they are very unlikely to feed on animals. After all, it’s primarily the psionic energy that is possessed by intelligent creatures that Mind Flayers rely on for nourishment.

Think of it like a human eating grass.

You’re physically able to eat the grass, but you won’t enjoy it and you’ll get virtually no nutrients from it. You’d likely much rather have a cheeseburger or some pasta than be expected to be happy eating a handful of grass.


There was a time, thousands of years ago, when Illithids were the uncontested dominant power of the Inner Planes.

Traveling throughout the planes on massive flying vessels known as Nautiloids, they would harvest intelligent humanoids from hundreds of worlds within their reach. Some would be devoured, others would be used as slaves, and others would be specifically used to propagate the Illithid race.

Another race, known as the Gith, were particularly relied on for slave labor.

For centuries, the Gith were enslaved by the Illithids until they eventually rose up against the cruel, tentacled tyrants.

Within a single year, the Gith completely destroyed the Mind Flayers’ empire. The Illithids were slaughtered, the Nautiloids were destroyed, and every trace of the empire was reduced to dust.

Not content to stop there, the Gith began sending out hunting parties to locate and wipe out any remaining Mind Flayers that they could find.

Even now, centuries later, the Gith have never stopped their pursuit.


Following the Gith uprising, pockets of Mind Flayers still exist.

These colonies exist in vast underground spaces, most notably the Underdark. Despite their numbers, psionic abilities, and ferocity, Mind Flayers stay vigilant in defending their territory and, most importantly, their Elder Brain.

While it is primarily the Gith that they are on guard against, this serves them well against other foes such as Drow raids, miscellaneous terrors of the Underdark, and, of course, adventurers.

Mind Flayers work diligently towards their goal of restoring their once-vast empire. To reclaim the glory that they once had, these beings will spare no expense.

Because they dwell in subterranean lairs close to their food sources, it’s not uncommon for Mind Flayers to begin to meddle with local affairs. Using their psychic abilities to control important figures in local cities (such as rulers or officials), it can be very difficult to tell just how deep an Illithid plot actually goes.


Nothing is more important to a Mind Flayer colony than the Elder Brain. It’s exactly what you might imagine: a single colossal brain that every Illithid in the colony is linked to.

The Elder Brain’s range for connecting to the colony is typically about 5 miles. Mind Flayers who go beyond that range only do so under strict orders from the Elder Brain.

It can be difficult (if not impossible) to truly tell where the Elder Brain’s influence ends and the Illithid, itself, begins.

An Elder Brain

As a scheming and purely evil intellect, the Elder Brain keeps very tight control over the entire colony that surrounds it. In this way, each individual Illithid is simply a small extension of the Elder Brain’s influence.

Each Elder Brain considers itself to be of supreme importance and would hear nothing otherwise. However, they do vary from colony to colony. Some might be cruel and hateful while others are more like impartial sages or living libraries of all of the information the Illithids have collected.

As a giant brain, these beings are all but entirely incapable of movement. They must stay within their pools (where Illithid eggs are hatched) or else they would quickly dry up and wither away.


Everything within Mind Flayer culture revolves around serving the Elder Brain. Their minds are all linked together as a network which allows for quick organization and seamless functioning as each Illithid knows its exact role and purpose.

In the same way that the thralls created by a Mind Flayer are perfectly obedient to their master, so the Illithids are completely loyal to their Elder Brain.

This creates a culture of servitude and order in which any level of dissent or intrusion is immediately found and dealt with.


As a collective hivemind based on service to the Elder Brain, it’s no surprise that Mind Flayers are of lawful alignment.

Similarly, because they achieve their goals by enslaving others and… you know… eating brains… they’re pretty uniformly evil across the board.

However, there is one admittedly rare situation where the Lawful Evil alignment may not quite apply…


Mind Flayers largely stay within their tight-knit colonies and connected to the Elder Brain. However, some situations may arise that cause a Mind Flayer to no longer be under the control of the Elder Brain.

If the connections to the Elder Brain are broken (whether that’s because of their colony being destroyed or some other powerful intervention), an Illithid may find itself going rogue. With free will, it is now able to make decisions for itself and could reasonably choose to be good.

That said, the Gith would not care about the Illithid’s alignment and would still exterminate it on sight. Because of this, it would still be very wary of a Gith hunting party.

Most likely, the Illithid would look to set out and create its own colony for protection in some secretive location. However, it might be less adversarial and could even be a useful ally for the side of good.

Of course, all of this would fly out the window if it finds itself back in proximity of another Elder Brain.

Keep in mind, though, that a “good” Illithid would still need to eat brains. It might be fine with evil creatures of some intelligence, but it’s up to you if that’s possibly still too cruel of a fate…

Just don’t mistake a Mind Flayer that claims to be good as being entirely genuine. Keep in mind that they are very intelligent manipulators who may even seek to cultivate sympathy before ultimately devouring your brains once they have your trust.


In keeping with the goals of the Elder Brain, a Mind Flayer colony focuses on building a secure base of operations before beginning the work that they believe will restore their empire.

As incredibly intelligent creatures, they gather as much knowledge about the world as possible. Funneling all of this information into the Elder Brain as a type of massive repository of information, the colony focuses in perfect unison on their goals.

Some of these goals may be massive undertakings while others may seem simple by comparison. Nevertheless, any and all information is of use to the Illithids and their pursuit of the Grand Design.


Mind Flayers’ goals are entirely dependent on that of the Elder Brain that controls them. What one colony views as the top priority towards the Grand Design may not even be a consideration of another colony.

Some goals might include:

  • Construction of some method to repel and destroy the Gith
  • Rediscovering the secrets of building Nautiloids
  • Optimizing the flow of intelligent visitors to their lair as a food source. (Possibly via political influence, sowing rumors of ancient magic/ruins that would appeal to intellectuals, or even just dropping an entire city into the Underdark)

When attempting to conquer a humanoid settlement, one of three strategies is used by Illithids to achieve their goals.

They might seek to outright control the settlement’s population by turning the citizens into mindless thralls. If they can’t safely infiltrate the city, the Mind Flayers might instead focus on amplifying their Elder Brain’s powers to begin influencing the innocent people of the settlement that way.

On the other hand, it might be more efficient for the Mind Flayers to take control of a few key aspects of the settlement. Sabotaging the community from the shadows, they can orchestrate a steady decline as the settlement is destroyed from within and, therefore, incapable of defending against the Mind Flayers’ assault.

Lastly, the Elder Brain might instead dictate that total destruction is the answer. Releasing plagues, famine, and natural disasters upon the population, the goal becomes total annihilation.

To gain further knowledge of the settlement’s weaknesses, the Mind Flayers learn all they need to know by eating the brains of stragglers who live there.


Mind Flayers have very powerful psionic abilities that are the foundation of their abilities.

These range from their telepathic communication to their Mind Blast ability to their ability to create thralls.

Some Mind Flayers (such as the Mind Flayer Psion variant in Volo’s Guide to Monsters) dedicate themselves entirely to refining their innate psionic abilities. These Illithids are able to mimic certain spells purely with their own psionic abilities.

Others, however, might take an interest in studying Arcane magic.

While these are rare (and usually shunned within their own colonies), the mixture of psionic and arcane abilities make Mind Flayer Arcanists (on page 222 of the Monster Manual) particularly dangerous.


Mind Flayers are very rarely encountered alone even though encountering multiple Mind Flayers at a single time is somewhat rare.

Because of their ability to create thralls, any Mind Flayer that is going any distance away from the colony will have some extra protection.

Most commonly, these thralls are captured humanoids, Duergar, Grimlocks, Kuo-Toa, and Quaggoths. Of course, anything that ventures too close to the Illithids’ grounds might be forced to serve as a thrall.

Imagine what could be done with an Ogre thrall!

Of course, the experiments conducted by Mind Flayers have also led to the creation of additional creatures that adventurers should be wary of.

For instance, a Beholder that has been implanted with an Illithid tadpole becomes a creature known as a Mindwitness. (Think of it as a beholder with less eyes and more tentacles that serves as an amplifier for the Elder Brain’s psychic connections.)

Other such creations include Neothelids (a tadpole that is never implanted in a host that grows unchecked until it is as gargantuan as a Purple Worm and, somehow, even more hungry) and the infamous Intellect Devourers (which made our list of 12 Monsters That Will Instantly Kill Your Characters).


With Mind Flayers being one of the original iconic monsters from the very earliest days of Dungeons & Dragons, there is no shortage of variations on these creatures.

However, the primary variations that have been officially published in the 5e materials at this point include:

  • Mind Flayer Arcanist – A Mind Flayer that mixes arcane magic with its own psionic abilities to dangerous effect.
  • Mind Flayer Psion – A Mind Flayer that has amplified its psionic abilities to further mimic other arcane spells in inventive ways.
  • Alhoon (Illithilich) – A Mind Flayer that has been exiled from its colony for pursuing studies of Arcane magic and successfully undergone a uniquely-Illithid process of becoming a lich.
  • Ulitharid – A very rare but powerful type of Mind Flayer that is capable of starting its own colony and becoming an Elder Brain itself.


Whew! There’s a lot to Mind Flayers, eh?

Now that we’ve covered what they are, let’s get into the practical stuff: how they affect your game!


Mind Flayers have good mental stats, but their physical skills aren’t as good. With low Strength, Dexterity, and Constitution, one could be taken down if you could get on top of it quickly.

The Mind Flayer’s Mind Blast, on the other hand, could potentially stun the whole group and cause one or more characters to die.

Spells that give the target a chance to make a saving throw won’t work very well in this fight, at least not against the Mind Flayer. This is because the tentacled ones are naturally resistant to magical effects. Though you can do damage from a safe distance with spells like Magic Missile and Fire Bolt.

The biggest threats when fighting a Mind Flayer (not including its allies in the fight) are its Mind Blast and Dominate Monster abilities.

With Mind Blast, the Mind Flayer will have no difficulty at all extracting the brain of at least one character. Needless to say, that character will be very dead if this happens…

Likewise, if the Mind Flayer is able to successfully use Dominate Monster on one of your party members, things can go bad very quickly.

Ultimately, you want to have a strategy and be able to execute on it quickly. If possible, try to keep a safe distance and don’t be afraid to use your Inspiration when the Illithid uses its Mind Blast if you have it.

Ranged combatants like archers are your best bet when fighting a Mind Flayer. They’re able to keep a safe distance, use the terrain to their advantage, and keep their target locked down with a storm of arrows.

The longer a fight with a Mind Flayer goes on, the less likelihood there is of you getting away.

Also, as one user points out here on Stack Exchange, use spells like Protection from Evil and Good to better resist the Mind Flayer’s attacks and be immune to the Charm effect from Dominate Monster. (Even though that discussion is about Pathfinder, this advice still applies in 5e!)


Mind Flayers are incredibly intelligent and very well-informed.

If combat is unavoidable for a Mind Flayer, you can absolutely bet that it’s prepared. With a few thralls or even a couple of Intellect Devourers, the fight can quickly become deadly for the party.

The Mind Flayer will look for the quickest ways to incapacitate the biggest threats. Mercy isn’t in the Illithid playbook, so don’t be afraid to be ruthless with its tactics!

After all, as a creature with a 19 Intelligence, the Mind Flayer should absolutely play strategically.

If the party is clustering together, the stun effect from its Mind Blast will make them into sitting ducks. A 60-foot cone can be devastating!

Otherwise, dominating the heaviest hitter and turning them against their allies can do the trick.

Though, you might also consider having the Mind Flayer dominate the party’s ranged attacker instead. Not only does the Mind Flayer gain an ally, but the party’s best counter to the Mind Flayer’s tactics isn’t on their side anymore!

If you want to get extra tactical when using a Mind Flayer, I’d suggest grabbing a copy of The Monsters Know What They’re Doing. You’ll have a hard time not letting out the classic “mad scientist laugh” when you plan the encounter with this book’s help.

You can learn more about TMKWTD in my review.


After a hard-fought battle with a Mind Flayer or, even harder still, a colony, the party probably is expecting some kind of epic treasure horde.

Unfortunately, Mind Flayers don’t particularly care about treasure in that way. Piles of gold and precious gems mean nothing to them and don’t serve to further their agenda.

I get it, but it kind of feels like a gut punch to go through such a difficult fight only to receive nothing.

While a ton of wealth doesn’t particularly make sense, I would suggest looking at options for magical items that you can give the party as a reward.

Perhaps the Mind Flayers were attempting to study the magical items or they were thrown to the side as the previous owner had their brain devoured.

For surviving their encounter with such a terrifying being, the characters absolutely deserve some kind of reward beyond the warm fuzzies they get for making the land at least a little safer.


What can I say? Mind Flayers has a lot to offer. Why else have these been around for so long? They are scary and have a lot of stories behind them. Because of how they work, they can be pretty easily added to almost any campaign without making it feel too forced.

Have you ever used a Mind Flayer or fought against one?

Tell me in the comments how that went!

Until next time!

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