Intellect devourer

Intellect devourers were psionic aberrations that took the form of walking brains. They were servants of the mind flayers and one of the most dreaded threats of the Underdark, with their power to consume intelligence and possess host bodies. "Don't cry. We have no intention of eating your brain. In fact, your brain is going on a wonderful journey!"

- Qorik El-Slurrk, a mind flayer

Description
They looked like little more than disembodied brains that could walk on a set of four bestial legs with clawed feet. They were about as big as dogs and despite their appearance, they could and attack with shocking speed. Their brain matter was protected under a crusty coating or a glistening, clear membrane.

Abilities
They were capable of magically consuming a humanoid creature's mind and memories from a distance of up to, provided that creature had a brain and succumbed to its psychic assault. If so, the victim's mentality was deteriorated. In the worst case, the victim's intellectual capacity was completely erased, leaving them dazed or stunned and ultimately incapacitated. Psionic intellect devourers instead consumed the victim's charisma, as with the ego whip power.

If the intellect devourer approached a vulnerable victim (whether incapacitated or already devoured) within, it could then battle the brain's remaining defenses; a protection from evil and good spell prevented this. If successful, it magically or psionically consumed the physical brain, then teleported inside the skull to replace the brain, whereupon it could use it as a host. Naturally, this killed the victim. A fresh corpse could also be used as a host, but not undead and other kinds of creatures not especially hampered by the loss of a brain. Any difference in size was taken care of by their compression power.

Once in control of its host, an intellect devourer had full control of the body, which was more or less as strong and capable as it was normally, while the devourer retained its own mental abilities. Moreover, the intellect devourer possessed partial or complete knowledge of everything the victim had known, including all languages surface knowledge of identity and personality but no specific memories or information,  or even all their knowledge and even their spells.. However, it would likely lose this knowledge once it vacated the host body.

Safely ensconced inside the host body, it could not be easily attacked or targeted itself. It could only be removed by a protection from evil and good. However, this process killed the host body unless the original brain was somehow restored within a few seconds. Alternatively, a wish spell could restore the host's brain, forcing the intellect devourer out. If the host body was killed or the intellect devourer was forced to leave by some means, then it teleported to a place away. An intellect devourer could also leave willingly, by exploding out of the skull. Otherwise, it could control the body for up to seven days.

To aid in hunting, an intellect devourer could detect the minds of sentient creatures up to a distance of, determining both presence and position. Walls and other barriers made no difference, but a mind blank spell rendered the mind effectively invisible. Some could also detect psionics. Otherwise, having no eyes, an intellect devourer could not be blinded nor assailed by magical gazes, yet could, by nonvisual senses, effectively "see" with blindsight up to and pinpoint all creatures in range.

They could communicate via telepathy to. Otherwise, they could not speak, though they could understand a language, such as the Deep Speech used by mind flayers or even Common. If in a host, however, they could use the body to speak with.

Some intellect devourers were capable of various other psionic powers, namely cloud mind to creep about unnoticed, compression to shrink and conceal themselves, empty mind to fortify their own mental defenses and intellect fortress to shield their bodies, id insinuation to confuse a few opponents, body adjustment to heal themselves, and painful strike to enhance their claws. They were highly shielded against psionics themselves.

Despite their exposed brains, an intellect devourer was protected by a crusty covering or clear membrane and was resistant to physical harm. They sometimes required an adamantine weapon to effectively harm and were immune to fire and highly resistant to electricity.

They were naturally skilled in stealth, deception, and hearing.

They fought using their clawed feet.

Tactics
Intellect devourers would wander the tunnels and caves of the Underdark on the hunt for sentient prey. When they sensed prey, they hid, using their powers to aid them, then waited for their chosen victim to be alone. It would then attack with all its psychic powers, before charging in to finish them off with their claws.

Afterward, the intellect devourer could seize the victim as a host and thereby infiltrate areas that offered it even more sentient minds to prey upon.

Ecology
The intellect devourer, as the name suggested, consumed the intelligence of sentient creatures. They would feed until the victim was no more than a mindless husk.

Illithids bred intellect devourers by subjecting the brain of one of their thralls to a ritual in which the brain sprouted legs and became an independent, intelligent predator. They created intellect devourers from the brains they elected not to eat themselves.

However, it was also reported that intellect devourers arose from the remaining brains of creatures slain by other intellect devourers. In this version, they seemed to be psychic parasites spawned by the insanity of the Far Realm and they still bore its taint.

Either way, the newly created aberration began its existence in a larval form called an ustilagor. These lived like rats and other vermin, only scavenging off the mental energies of bigger creatures and were farmed as a delicacy by illithids unless raised to maturity.

A mature intellect devourer, also called an intellect predator to distinguish it from the other stages of life, operated similarly to a wolf. They hunted in packs known as 'pods' of up to four specimens, but they could also hunt alone.

Rarely, an intellect predator that lived a long time and grown massive on consumed intelligence underwent a second metamorphosis, becoming what was known as an intellect glutton or brain collector. Too big to take a host body, these powerful creatures in their own right.

Habitats
These predators were found prowling the underground and in the Underdark, independently and in service to the illithids. They were usually found near other aberrant beings, particularly the mind flayers.

In the Abyss, they could be found in Shedaklah, the Slime Pits, the 222 layer of the Abyss.

Usage
Illithids used their intellect devourers for hunting. Normally, they had them possess and puppeteer the bodies of their victims and then use them to lure other creatures into the illithids' hunting grounds, so the mind flayers could consume their brains themselves or dominate them as new thralls. Otherwise, they kept them as guard beasts and even as pets, while an intellect glutton might be ridden as a mount.

More generally, other intelligent creatures who dared to use intellect devourers would set them to work as guardians or as predators for some purpose. By taking a host body and posting as their last victim, they made for excellent spies.

Appearances

 * Adventures
 * Waterdeep: Dragon Heist • Waterdeep: Dungeon of the Mad Mage
 * Video Games
 * Neverwinter Nights • Baldur's Gate III
 * Card Games
 * AD&D Trading Cards
 * Board Games
 * Faerûn Under Siege • Betrayal at Baldur's Gate • Dungeons & Dragons Dice Masters: Trouble in Waterdeep • Dungeons & Dragons Adventure Begins
 * Film & Television
 * ''Honor Among Thieves