When the movie poster for Dungeons & Dragons: Honor Among Thieves was first revealed, quite a few eyebrows were raised on account of one monster. 

Classified as tiny aberrations, these monsters look like brains made ambulatory by four furry and clawed legs. If that sounds like something out of Dr. Frankenstein’s lab you’d not be far off. Bred by mind flayers — who may also have been teased in the controversial poster as the creature with tentacles — intellect devourers serve as hunters in the Underdark. Since it's already been established that the movie has scenes in the Underdark, it tracks that these creatures would show up there. Intellect devourers have been featured in Waterdeep: Dragon Heist and Waterdeep: Dungeon of the Mad Mage which could mean the characters in the movie make their way through the City of Splendors either to reach or escape from the Underdark through Undermountain.

SyFy Wire put intellect devourers on a list of “The 9 Scariest, Most Unforgettable Monsters from Dungeons & Dragons.” Of all the creatures in the Monster Manual, this one likely elicits the most “burn it with fire” vibes, and it’s not just because of how it looks. An intellect devourer does exactly what its name says. It gobbles up minds and memories. And if that’s not bad enough, when it’s done with its psychic snack it gains full control of its victim’s body. You read that right: a character becomes the intellect devourer’s puppet! The basic idea is that a “ritual” occurs. In game terms that means the aberration initiates an Intelligence contest with an incapacitated humanoid — way to kick someone when they’re down! If it wins, the intellect devourer magically slurps up the target’s brain before teleporting into the skull and taking control of the body.

If you’re a DM who wants to subject your players to some truly horrific monsters, aberrations like the intellect devourer would certainly be a choice. These creatures serve the interests of their mind flayer masters, who in turn serve the elder brain in a monstrous kind of MLM. So, where there are intellect devourers, there are other aberrations. These tiny creatures aren’t just wandering around willy-nilly. Unless an adventuring party stumbles upon them in their “natural” habitat, they’re probably piloting an NPC like a fleshy mecha.

An intellect devourer is a creature of high Dexterity and Constitution but low Strength. It’s also smart enough to know that if it runs around in its brain-on-legs form, someone is bound to set it on fire. All things considered, the aberration likely uses Stealth to sneak up on its prey. They have an ability called detect sentience that basically allows them to geocache for humanoid brains. Woe especially to the PC who decided to make Intelligence their dump stat because from there the intellect devourer makes one attack with its claws and uses its devour intellect action. This is where it truly does a target dirty. It makes attacks that not only do psychic damage, but also reduces the Intelligence of a humanoid with a brain, continuing to do so until it reaches 0. At that point, the target is incapacitated and in prime form for brain snacks using with the intellect devourer’s body thief action (described above).

If you’re a player whose DM just subjected you to this creature, you’re probably wondering what now? While nesting in your character’s skull, the intellect devourer has total cover against attacks and other effects originating from the outside. Although it retains some of its traits, the aberration also adopts your PC’s statistics. That’s right: it knows everything your character knew, including spells and languages. With that knowledge, it uses the host's body to lure others (like the rest of the adventuring party) to their untimely deaths at the hands of its mind flayer creators.

Outside of dying, which obviously isn’t ideal, there are a few ways to extract an intellect devourer but they pretty much all involve your friends knowing that you’re literally not right in the head. Driving the aberration out isn’t going to solve for the fact that your brain was magically removed either. Without replacing said brain, if the intellect devourer is evicted for squatting, a character dies after 1 round. A wish spell is pretty much the only way to return the brain to its rightful owner. Overall, even though the D&D version of an intellect devourer looks like a brain-dog, 0/10 would not recommend petting one.