Mind Flayers 5e
Guide by Sam West, @CrierKobold
See also: aboleth, alhoon, elder brain, gith, neothelid, and intellect devourer
Baulder’s Gate 3 graced the world with some of the best illithid action we’ve ever seen, and you might be taking inspiration from this fantastic media to brew some villainous brain suckers into your own games. Here, we’re going to dive into what makes Mind Flayers work, how to support them in combat, what tactics they employ, and if you’re a player, things to do to combat these aberration overlords seeking total domination of time and space.
For more on Mind Flayers, my number one recommendation is Volo’s Guide to Monsters. It has additional stat blocks for Mind Flayer variants as well as plenty of fantastic lore about these villains. Fizban’s Treasury of Dragons also has some bonus stuff for mixing mind flayers with dragons, as seen in its Elder Brain Dragon.
Running the Monster
Mind Flayers are a CR 7 aberration with a wide spectrum of options available- they get psionic spellcasting for two at-will spells and a once-per-day Dominate Monster and Plane Shift. On top of these spells, they have a mind blast ability that releases a cone of psychic destruction that recharges every two to three rounds on average. What they tend to be most known for, though, is their tentacles and extract brain attacks, which pose as lethal weapons that can end 5th through 10th-level characters in a single bite.
Player Level
Given their kit, these villains tend to be limited to upper-tier play. Their mind blast deals 22 damage on average, making it instantly drop 5th level and under characters, and for those who don’t fall in a round, the stun can prove to be close to a death sentence.
Players starting at 6th to 7th level can take one on, but the fight will be largely about how many hits the players can get in against it before it gets an opportunity to mind blast. If the players get the drop on it, the encounter can end in a single round, as its only defenses are its 15 AC, 71 hit points, and magic resistance.
If it gets the drop on the players and is in a kill-or-be-killed mentality, it can come down to whether Dominate Monster successfully takes control over the party’s paladin or barbarian. That outcome can flip the fight into a precarious situation where multiple party members are losing turns to stuns while doing whatever they can to avoid getting mutilated by their mind-controlled ally, usually resulting in one or more player deaths.
10th level and higher groups won’t have too much trouble dealing with a single Mind Flayer; multiples radically increase the challenge of the encounter. They have two stuns on their sheet and one spell that takes complete control of a monster; if these abilities work, the party is going to get thrashed.
Defining Gameplay to Work With
Mind Flayers have two stuns on their sheet and one full-player control spell. These two elements set them up to have an easy time debilitating party actions and can be incredibly frustrating for some groups to engage with. Their entire identity is stunning creatures and eating their brains one at a time with the tentacle into extract brain combo. Sitting around helplessly failing save after save and watching as your character dies can be infuriating, especially should the rest of the group have similar luck when it comes to dealing with the stuns it puts out.
Detect Thoughts at-will can make them alert to danger- they can sense any creature within 30 feet of them, making ambushes require planning and distance. If they suspect infiltration at all, they likely will regularly be scanning for interlopers.
Mentality and Tactics
Mind Flayers have a pretty clear game plan given their tools- they want to get a Dominate Monster down as soon as or just before a fight breaks out. Mind Blast helps further reduce the party’s actions with an area of effect stun; this tends to give them a clear target to seek out in melee range that they can follow up with a tentacle attack. Their tentacle can stun the victim again, and extract it’s brain next turn for lethal damage while their mind-controlled minion keeps them safe while they dine.
The name of the game for them is isolation- get one party member stunned on their own while others deal with other problems, be that the mind blast stun, the dominated party member, or a group of minions. An isolated target is ripe for brain extraction, as once stunned, they’re going to be as good as dead without outside intervention.
Plane Shift is a great “break in case of emergency” mechanic they can use to dip should a fight not look fair or profitable to them.
There are some hiccups with the monster; concentration makes their levitation-at-will ability feel terrible, as they can’t both concentrate on staying safely off the ground and mind control a party member. Usually, that just means they don’t choose to levitate, or only start levitating once Dominate Monster wears off.
Combating the Monster
Mind Flayers are highly challenging monsters when run as tactical, villainous masterminds. They’re aware of their own limitations, and have an easy escape route always available to them should death seem likely. You can employ some tactics to fight against it, and some tools to seek out if you need to take it down for good.
Methods of Engagement
Mind Flayers have such a robust suite of abilities I want to tackle them one at a time- having a plan for the varying effects can massively improve your odds of survival and success.
Dominate Monster: The first thought to take into a Mind Flayer fight is simple: how do you deal with Dominate Monster? If you don’t have a good answer to that question, the fight can be brutal. Fortunately, there are some precautions you can take against it. It imposes the charmed condition, making any methods for gaining immunity to or advantage against the charmed condition a method for preventing domination outright.
Fey ancestry is the most common defense (which a decent smattering of creatures get), and bards can get Countercharm to offer up advantage. Paladins come with an Aura of Protection which adds a boost to saves, making the DC far more manageable for a myriad of characters.
Should it land anyway, the best way to end the effect is simply to hit the mind flayer. It's a concentration spell- damage can end the effect, so laying into it usually can get the effect to end while also moving you closer to victory.
Mind Blast: Once you’ve established what to do about the Dominate Monster, which usually looks like “stand near the paladin” or “be ready to cast Counterspell”, you’ve got Mind Blast to worry about. This time, standing near the paladin can be detrimental, as it hits a 60 ft. cone out from the monster. Cones are fickle, though, and pretty easy to take advantage of- the solution is to get on multiple sides of the monster to prevent it from hitting multiple targets.
In a perfect world, this can look like being within 10 feet of the paladin for their aura while being on opposite sides of the monster.
Otherwise, boons to saves help here as well, as does resistance to psychic damage if you can find cheap means to get it.
Tentacle and Extract Brain: These two abilities only will come up if things are going badly. When they are, though, you’ll need an escape plan. If you are hit by a tentacle, you’re going to get a contested athletics or acrobatics or get stunned for however long it has you. While you’re stunned by it, you can’t spend your action trying to break free because, well, you’re stunned. This leaves it up to somebody else to get you out.
Once again, being up in the illithid’s business is the best method for keeping the entire group alive. With only 71 hit points, attacking it should still probably be the route to take, as a dead mind flayer can’t eat anyone’s brains.
Combatting Plane Shift
If you’re intending to kill a Mind Flayer, you need a way to prevent it from Plane Shifting away. There are two main ways to arrange this; first, you can goad them to use it to get to you. If you’re at a stage in which you can traverse planes, tempting the illithid into a trap it has to Plane Shift into disables its escape mechancism. That’s not usually on the table, though, and requires you have the means to outwit creatures who are designed to be geniuses.
Alternatively, you want ways to disable their spellcasting. Spells that deny actions like Hold Monster are an easy place start, as if they can’t take actions, they can’t escape. Silence and Counterspell can server similar purposes, as they can prevent the escape premptively or as its being cast.
You can also attack their Material component; disarming them of their spell focus prevents Plane Shift from functioning, as would removing their attuned fork worth 250 gold or more.
You’ll want a plan of attack going into the encounter for this- either you need to burst through its hit points, or have a way to interact with Plane Shift or the mind flayer will flee to fight another day.
Classes That Shine Against It
Paladins offer a save boon to their allies that stick close to them. Avoiding getting stunned outright makes the encounter a breeze, and they are one of the best classes to enable that defensive measure.
Similarly, classes with proficiency with Int saves (Artificer, Druid, Rogue, and Wizard) all are more likely to handle the saves better than Barbarians and Fighters who are dumb as bricks.
Dominate Monster uses a Wis save, notably, meaning Druids and Wizards have proficiency in both saves the flayers are going to be throwing against the group.
After defensive considerations, having classes with access to ways to interact with its spellcasting is useful. Wizards again come with Counterspell access and ways to disable its actions. These two elements can prevent its escape while the other team members wail on it to kill it for good.
The World Around It
Mind Flayers I’d argue are the current best big-bad that’s directly tied to the world D&D is played in, the Forgotten Realms. They’ve even usurped dragons as the top villains of the universe- they’re weird, alien monsters that need to subsist on brains to exist. They’re dominating invaders from another world who subjugate entire species. Mind Flayers are top-notch, unapologetic villains with the brains to reasonably pose a threat to societies.
As the Main Antagonist
A single Mind Flayer with its bare-bones stat block has all the tools it needs to be a huge problem for the world around it. Its Detect Thoughts fluff allows it to passively control groups of underdark denizens which it then uses as both food and a means of asserting control over a region.
Lone mind flayers can work in the shadows. They don’t need to be observed to function- they don’t crave attention or worship like other egotistical villains. Illithids are schemers and planners. The players might not know they’re against an illithid until they physically meet it briefly before it shifts away. This adds layers of intrigue along with ample room to hint at the villain’s true nature.
Lone Illithid Underling Table
| d6 | Underling |
|---|---|
| 1 | A group of kuo-tao, once controlled by an aboleth the Illithid had killed |
| 2 | A collective of once-warring tribes of troglodytes |
| 3 | A squad of ogres who are entirely unaware of who is giving them their ideas |
| 4 | Quagoth’s used as beasts of burden and a food source |
| 5 | A drow noble and their house’s militia, desperate for power |
| 6 | The last of a once thriving community of grimlock hunters eradicated by the flayer |
Illithid groups quickly can become a problem for the worlds they reside in, like a festering parasite in its guts. A Mother Brain controlling these groups is a challenge for upper-tier characters, sometimes growing to the point where you’ll need 8th and 9th-level spells to begin combatting their power. Regions can fall to a shadow council of flayers who regularly dominate lords of the lands, commanding them, and through them, their armies, to assert control over the masses without drawing attention to their secret works to eventually acquire complete and total domination of the plane.
Environments
Illthids can slot into just about any environment, as they’re otherworldly invaders who don’t much care for where they are, just that they have sufficient food to fuel them as they plot their way into power.
Subtle signs of Mind Flayers can hint at their presence. Usually, they’re going to do a good job obscuring where they are and what they’re doing, but they may get sloppy when hungry or desperate.
Signs of Mind Flayers
| d6 | Sign of Nearby Mind Flayers |
|---|---|
| 1 | A corpse of a humanoid was found entirely intact- minus its scalp and brain. |
| 2 | A group of normally hostile or raucous humanoids are oddly passive, working in a manner unusual for their species. |
| 3 | You’re thoughts are interrupted, as if another presence briefly touched them before disappearing from your mind. |
| 4 | A town has far more houses than its current population, all of which continually tell you nothing is wrong, and that you should move on from here with strained smiles. |
| 5 | Otherworldly runes and sigils are etched into a spherical room with a central chair in the middle; this is one of the Flayer’s attempts at rebuilding their crashed vessel. |
| 6 | A hidden room below a palace, down several stories, contains humanoid holding capsules and a vat of leech-like creatures. |
Quest Hooks
If you want to start a series of quests to confront a mind flayer, I’d consider starting a few steps away from the illithid’s location. Instead of directly confronting it as it attempts an evil act, you’ll have the players confront its minions performing tasks for the mind flayer which can act as a jumping-off point to delve further into the mystery.
You can start with the Mind Flayer Machinations table to work out what their end goal is, and then pair it with some quest hooks to build out a narrative and series of quests around this Mind Flayer enacting its evil schemes.
Mind Flayer Machinations
| d6 | Scheme |
|---|---|
| 1 | Having crashed here, the Mind Flayer seeks to repair their ship, reconvene with their colony, and herald an invasion of this prosperous area. |
| 2 | Exiled from their colony, the vengeful illithid is building an army to take this plane and go to war with their old Elder Brain and colony. |
| 3 | The Mind Flayer seeks to subsist in hiding from the Gith hunting it, eventually regrowing its colony to eventually take vengeance against its hunters. |
| 4 | Worshipping an eldritch being from beyond the astral, the Mind Flayer has begun rituals to summon it to this world to enslave humanity and bring an illithid paradise. |
| 5 | The Mind Flayer has deep routes in society and has decided to take control over every region to bring about eternal peace by enthralling all humanoids. |
| 6 | An Aboleth is at war with the Mind Flayer, both sending their thralls at each other vying for control over the region, collateral damage splashing all around the region. |
Quest Hook Table
| d4 | Quest Hook |
|---|---|
| 1 | A band of brigands has cornered off a mysterious bog, and refuses to allow anyone to pass near it. |
| 2 | A local noble has begun acting strangely and has started funneling resources into a war effort they prior were opposed to . |
| 3 | People have been disappearing around a popular pub late in the night, and nobody seems to be able to remember where they went. |
| 4 | Caravans are being raided regularly by underdark creatures who prior never breached above ground. |
Associated Loot
Mind Flayers have as much use for magic items as the players do; their loot being useful tools they use the players can find uses for can be a big thematic win. There are stories to tell about the deeds the illithid committed; a vorpal sword may be a trophy mounted above its desk as a reminder of the champion who it got the best of and ate. For the players, now that trophy becomes a weapon in their tool box, passed from hero to monster and back to the heroes.
Mind Flayer Items Table
| d12 | Item |
|---|---|
| 1 | Amulet of the Planes |
| 2 | Animated Shield |
| 3 | Crystal Ball |
| 4 | Helm of Brilliance |
| 5 | Helm of Teleportation |
| 6 | Portable Hole |
| 7 | Ring of Evasion |
| 8 | Ring of Regeneration |
| 9 | Robe of Eyes |
| 10 | Robe of Stars |
| 11 | Staff of Thunder and Lightning |
| 12 | Wand of Polymorph |
Everything You Need to Feast on Player Brains
With these tools and ideas, go forth with your Mind Flayers, or prepare to face against them! Running them can be a challenge, especially depending on groups who get particularly frustrated with their stuns, but I do think they’re worth messing around with. They can be fantastic villains with complex objectives and motivations that will challenge the players in a way dumber villains cannot.
Now bust out your inky tentacles, and get to brain extracting!
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