Few low-level Dungeons and Dragons monsters are as intimidating to see on a DnD battlefield as the star of this Intellect Devourer 5e guide. Not only is its appearance off-putting enough to send a shiver down any adventurer’s spine, but the creature can kill a player’s character with relative ease and exploit the weak mental ability scores of martial characters.
I’ve used Intellect Devourers numerous times throughout my D&D campaigns and have used them to create some really great story beats. So, if you want to challenge your players or give them something in the world to fear, consider throwing an Intellect Devourer their way.
Key Info Up Front
- Book: Monster’s Manual, page 191
- Type: Aberration
- Size: Tiny
- Challenge Rating: 2
- Terrain: Underground
Intellect Devourer History in DnD
The Intellect Devourer was featured in 1e and has remained the same ever since. This is surprising and a tad terrifying, as 1e was a brutal system where player characters could quickly die from a single wrong decision or failed saving throw. This approach to difficulty has been largely abandoned over the years, but the Intellect Devourer brings some of that punishing design to 5e.
Throughout the editions, the Intellect Devourer has also changed very little in its abilities and appearance. They have always been small to tiny evil creatures that resemble a human brain that crawls around on four bestial limbs.
Their lack of a mouth means they cannot speak, but they understand Deep Speech or Undercommon and can speak telepathically with others. Interestingly, the main thing that has changed over time has been their challenge rating.
In 5e, they are rated as only a challenge rating of 2, but in 3e, they were ranked much higher at 7.
Intellect Devourer Lore
Illithids, more commonly known as Mind Flayers, are humanoid creatures that rule over the Underdark and can be identified by the long tentacles that sprout from their face. They possess mighty psionic powers in their blood and are well-feared among all life forms because of their ability to control the minds of other living creatures. Sometimes they instead consume the brains of the living by having their tentacles slither into the skull of their victims to eat them while they are still alive.
They are all driven by an insatiable desire for racial supremacy. While all Illithid don’t necessarily work together to achieve their goals, their cultures and upbringing almost guarantee that everyone believes in the superiority of their race.
They are driven to dominate the minds of weaker races so that their societies can rise from the caves and tunnels they have defeated for generations to rule over the overworld. Then, they believe they will act as agents of order that can contain and control the chaotic world, puppeteering it into their ideal image.
To work toward this end, the Illithid runs an oppressive civilization fueled by slaves, dubbed thralls. These thralls are grown for their brains to feed the Illithid, perform manual labor, and create other creatures to carry out their orders, like Intellect Devourers. Using their armies of thralls and controlled creatures, they operate from the shadows of the Forgotten Realms to manipulate and control the overworld.
In this way, they are able to shape the world into more favorable positions for their designs. Intellect Devourers play a key role in these schemes, especially when neutralizing heroic threats and controlling essential people in the overworld.
Intellect Devourers’ Place in Illithid Society
Intellect Devourers are only created by Mind Flayers. There are no naturally occurring Intellect Devourers except in the Abyss plane. They are created by Illithids that perform a complicated ritual on the brain of a sentient creature, which causes it to sprout bestial legs and become covered in a crusty shell that protects the brain.
They were first created in a larval form known as an Ustilagor, which has only been featured in 1e, 3e, and 4e so far. Ustilagor look like a human brain with two tentacles extending from it, and they can either be raised to become Intellect Devourers or can be eaten by Illithids as a delicacy.
For an Ustilagor to grow to an Intellect Devourer, it has to consume other creatures’ thoughts and mental energy to sustain their growth. While they are much weaker than adult Intellect Devourers, they are still capable hunters thanks to a highly patient approach. They are known to be capable of stalking their prey for hours at a time until they can ambush them to consume their memories and thoughts. With that energy, they can grow and develop into a full Intellect Devourer over time.
Once Intellect Devourers are fully grown, they tend to fulfill one of a few roles in Illithid society. Their most common role is as pets and guard animals. While Intellect Devourers may not be competent fighters in a traditional sense, they are still well feared by denizens of the Underdark.
They also can be used to infiltrate the political systems and civilizations of the overworld that the Illithid wish to conquer and dominate. To do so, Illithids capture rulers, generals, and lawmen, allowing Intellect Devourers to consume their brains and control their bodies.
When this is done, the Intellect Devourer learns everything that the person knew, including how to imitate them almost imperceptibly. The controlled person can then be returned to the overworld so that they pretend to return and continue living that person’s life, only under the control of their Illithid overlord. Some other Intellect Devourers are instead used to try and remove the greatest threats to the designs of the Illithids, especially great heroes.
These Intellect Devourers present the greatest threat to players, especially when traveling through the Underdark. They hunt down their prey to try and kill or dominate the hero and use them to help the Illithids. This makes them one of the most powerful parts of the Illithid’s arsenal, especially when targeting enemies with lower mental ability scores.
Intellect Devourer Stats
While the Intellect Devourer is very scary for player characters regardless of their level, their base ability scores are pretty pitiful. Their highest score is Dexterity, which is only level 14, closely followed by a Constitution score of 13 and Intelligence of 12. That half of ability scores are its only positive modifiers, as their Wisdom is 11, their Charisma is 10, and they come with an almost useless Strength of only 6, which comes with a modifier of -2.
However, their skills come with a +4 Stealth and +2 Perception, which help them sneak up on their prey as well as their Tiny size. Since they don’t have any eyes or other organs, they can only sense through blindsight, which has a range of 60 feet. To make fighting an Intellect Devourer slightly more challenging, they also are immune to being blinded and are resistant to any damage from nonmagical weapons regardless of the damage type.
Since Intellect Devourers are only Challenge Rating 2, it is not very surprising that they have a meager armor class of 12 and a maximum of only 21 hit points. However, they have a speed of 40 feet, as well as the unique Detect Sentience feature. This feature allows them to detect the exact location of any creature with at least three Intelligence within 300 feet of them. The only way for a creature to avoid being detected by this feature is if they are under the effects of the spell mind blank.
Intellect Devourer Abilities
The terrifying part of facing an Intellect Devourer comes from their combat actions. They have some basic activities such as their Claws attack and a Multiattack that allows them to use their Claws and Devour Intellect actions once each. Their Claws action is made with a +4 attack modifier, and it deals 2d4 + 2 slashing damage, which averages out to 7 damage.
The Devour Intellect action is one of the Intellect Devourer’s most frightening actions for martial characters. It allows them to force a creature within ten feet of them to make an Intelligence saving throw with a DC of 12. If the target fails the saving throw, they take 2d10 psychic damage or an average of 11.
After the failure, the Dungeon Master also rolls 3d6 and adds them together. If the total is greater than the target’s Intelligence score their Intelligence is instantly reduced to zero. This stuns the target until they somehow regain one Intelligence point to recover.
Finally, the Intellect Devourer has the Body Thief action, its flagship feature. It allows them to enter a mental battle with the mind of an incapacitated creature within five feet of them. If they successfully dominate their victim’s mind, they teleport into their skull and take control of their body. While the Intellect Devourer is in the creature’s body, they are considered to have full cover. They cannot be directly attacked by any source and kees its own mental ability scores while taking on the host’s physical ability scores.
When an Intellect Devourer takes control of a humanoid’s body, they also learn everything that the creature knew, including any languages or behaviors. Upon teleporting into the person’s head, they also destroy their brain. This means that if the Intellect Devourer is removed from the body, the host is left dead unless their brain is restored within one round. However, how the brain can be restored in that time is not described in 5e’s official rules and will be at the discretion of the game’s dungeon master.
The only way to remove an Intellect Devourer from a host, however, is by having the host drop to zero hit points or the wish and protection from evil and good spells. However, the Intellect Devourer can also willingly teleport out of the host to an unoccupied spot within five feet of the host.
Playing an Intellect Devourer
How you ultimately play an Intellect Devourer in combat will depend on the level of players in your party. If your party is at a low level, I recommend only having them face a single Intellect Devourer at a time. Unless the players in the party are also quite experienced, it also helps to give them some information about just how dangerous Intellect Devourers are before they encounter one.
If they don’t know just how dangerous of a situation they are in, it will not only make the problem not as exciting as it could be but also could lead to them not being careful enough. This can then lead to them feeling like it was an unbalanced or unfair encounter if they end up dying from it.
If you want to use an Intellect Devourer against a party of higher-level characters, you should also include other monsters in the encounter. This can be either Illithids or other Intellect Devourers. Either way, it is important to have multiple monsters in the fight, otherwise, a high-level party will destroy the Intellect Devourer before it can do anything.
Regardless of which approach you end up using, your Intellect Devourer should approach combat stealthfully out of the hope of avoiding as much direct combat as possible. You can even have your party be stalked by the monster for some time, giving them the chance to detect it with successful Perception checks to avoid getting surprised.
Once in combat, you should have the Intellect Devourer avoid melee combat as much as possible. They may have their Claws attack action, but their mental attacks are where their real strength lies. Suppose you have other monsters in the fight as well and want to make things difficult for your party.
In that case, you should have the Intellect Devourer focus on martial characters as they should have the lowest Intelligence score to protect them. The Intellect Devourer would be able to sense this and would consequentially target them.
You should also take full advantage of the Intellect Devourers’ base speed of 40 feet. This will be at least slightly higher than most player characters, allowing it to stay just out of attack range while it annoys the players with its attacks and abilities. This can help make the combat encounter take longer, giving the Intellect Devourer more time to work into a character’s head.
You should also note that it doesn’t entirely make sense for an Intellect Devourer to flee from combat, as they blindly follow their instructions from the Illithids with no regard for their safety.
After a Player is Dominated
Once one of your players becomes the host for an Intellect Devourer, there are a few different options for handling it. If you want to run a high-stakes campaign or follow the official 5e rules as much as possible, once this happens, the character is dead and nearly impossible to get back. That is unless your party has access to the wish spell.
If you plan on running an Intellect Devourer this way, I recommend only pitting it against high-level parties that can get access to a wish spell somehow, even if it is expensive. Otherwise, killing a character because of a bad save or two can be frustrating and even unfun for some players. Of course, if your group is all okay with a more hardcore campaign, you may want just to let it kill them so that it feels as dangerous as it should be.
If you want your party to be able to save their party member through the wish spell, it can be very effective to not give them that information immediately. If a party member can simply cast the wish spell, they will likely think of doing so quickly. Otherwise, you can use figuring out how to save the character as a fun side quest in the greater campaign.
This will challenge your party to keep their party member contained or under control until they figure it out, as well as give them a goal to work toward as they research and try to gather resources to perform the spell. If you want the process to take a while, though, I recommend giving the player whose character needs to be saved an NPC to control.
This will help avoid them having to sit out for hours of playtime while they wait for their character back. Or, you can always have them control their character under the influence of the Intellect Devourer to have them try to fight back if they think that would be fun to play.
Another option for ruling a player hosting an Intellect Devourer is one I’ve used and had a lot of fun with, if you don’t mind bending the standard rules of 5e a bit. When I used this approach in my campaign, my players loved it, and it led to a great short story arc. The basic idea is allowing the party to go into the mind of their party member to fight against the Intellect Devourer and safely remove it from the character’s mind.
To introduce this idea to your players, you can have them learn about it through their research or through a powerful NPC with magical powers the players may not entirely understand. Once they find a way into their party member’s minds, you can build a unique dungeon for them to go through. When I built my dungeon, I built its floor plan to resemble the sections of the human mind, with each room offering challenges and encounters themed around what that area of the mind does.
This helps the dungeon throw a lot of variety at your players, as well as giving inspiration for some enjoyable and trippy experiences that you wouldn’t usually find. Even better, since the dungeon is in the character’s mind, they can even appear as a mental image of themselves so that the host player can participate.
For example, you could have one dungeon room built around the real-world Cerebellum. This section could be shaped precisely like the Cerebellum and be built around how that section of the brain is responsible for the body’s muscle movements and coordination. So, if you’re designing the dungeon room, you can incorporate a puzzle that requires a party member to climb through obstacles or a hazardous trap built around circumventing a dangerous pit.
Then, you can also have the party go through a combat encounter against enemies that force them to make a lot of appropriately themed saving throws. If your party has exceptionally high Dexterity, you could even have the combat encounter incorporate the obstacles for some dynamic gameplay.
This structure also allows for a great roleplaying opportunity if your group is up for it. Delving into the mind of a player character is an easy setup for the rest of the party to witness some of the character’s history or pivotal parts of their psyche. Suppose the afflicted character is interesting in expanding their character’s personality and backstory.
In that case, a dungeon such as this can be an enjoyable way to do so by weaving those memories into the dungeon’s encounters and rooms. Doing so can help the dungeon become even more memorable by reaching emotional moments alongside its unique flavor and theme.
Question: How do you get rid of an Intellect Devourer?
Answer: The only official way to remove an Intellect Devourer in 5e is through reducing the host body to zero hit points or by using either wish or protection from evil and good spells. However, when the Intellect Devourer leaves the host’s body, the body is killed unless its original brain is restored within one combat round or roughly three seconds.
Question: Can a character survive being dominated by an Intellect Devourer?
Answer: In the 5e base rules, there is no way for a creature to survive being dominated by an Intellect Devourer except for the wish spell.
Question: Is the Intellect Devourer too powerful for a challenge rating of two?
Answer: With the Intellect Devourer’s low hit points and armor class, even a low-level party should be able to defeat an Intellect Devourer in combat. However, it may feel unfair to pit low-level players against such a dangerous creature, so I recommend adding the Intellect Devourer to higher-level combat encounters to add dynamic interactions for the players to react to.
Intellect Devourers are one of the most intimidating creatures in all of 5e, even if they are pitted against high-level characters. They are able to brutally punish players that have neglected their mental ability scores in a fashion that is rarely seen in the system and is instead reminiscent of the very first edition.
While this can make using one or two in an encounter feel like a risky idea for Dungeon Masters, with careful preparation, they can provide not only fantastic encounters but some exciting storytelling opportunities as well.