Illithids, more commonly known as Mind Flayers, are one of Dungeons & Dragons most dangerous and alien creatures. Their status as aliens was intentional, and likely inspired by the Old Gods of H.P. Lovecraft's imagination, as they travel the planes in search of civilizations to overpower and enslave. Mind Flayers are horrific abominations so alien those people they invade, and it's no wonder why they are one of the most feared enemies for adventurers to happen upon.

Mind Flayers think highly of themselves, often referring to themselves as masterminds. Their incredible intelligence and ability to psychically control those they invade and conquer makes them powerful and fearsome, but they do have their weaknesses. Escaping one with your mind (and brain) intact is a matter of finding and exploiting these.

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They're In Your Mind

These interplanar conquerors have been known to enslave their victims, using their psionic powers to dominate entire populations. Not only do their slaves carry out their bidding, but the more intelligent specimens also provide their Mind Flayer overlords with a seemingly never-ending supply of food.

Mind Flayers communicate telepathically, using their minds to convey their wants, needs and orders, but they can use physical speech if they need to. There is a danger to their psionic powers that can render them incapacitated (or even kill them) if they deplete their psychic energy reserves too often. The result is a deadly phenomenon known as psionic cascade. Mind Flayers can suffer from psychic flareback, which causes their spells to backfire and damage their psychic abilities.

Terrifying Little Tadpoles

Mind Flayers are humanoid in their appearance, and a full-grown Illithid can stand between six to six-and-a-half feet tall -- but they don't start out that way. Hermaphroditic in nature, an adult Mind Flayer will lay a clutch of about 1,000 eggs two or three times during their life cycle. Those eggs hatch into disgustingly adorable Illithid tadpoles, which take around 10 years to reach full maturity, though their odds of survival aren't very high.

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Eggs are laid in the tank of the Elder Brain the Mind Flayers serve, and they spend their early years battling other tadpoles for supremacy and developing their own psionic abilities. Many of them are actually eaten by the Elder Brain itself, but those who survive the maturation process grow up to become horrifying, squid-faced monsters that thrive on brains.

The Elder Brain

Mind Flayer life cycles are incredibly complex, and those who survive evolve into what is known as an Elder Brain. This giant brain exists within in a tank of brain-enriched nutrients and baby Mind Flayers. Because its only physical means of protecting itself are its tentacles, the community of Illithids surrounding it are tasked with its protection.

That is not to say Elder Brains are utterly defenseless. The consumption of intellect from the brains of dead Mind Flayers tossed into its tank add to its power and intelligence, granting it incredible psionic powers. Those psionics allow it to Mind Blast foes away from its tank and infiltrate their minds to control them with spells like Charm Person or Dominate Person. They also use their mental abilities to communicate with their community, filling them with dark dreams of ultimate domination over their prey.

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Delicious Brains

Calling these creatures "Mind Flayers" is appropriate on two levels because their powerful psionic abilities allow them to invade, manipulate and destroy the minds of their prey so they can be more easily enslaved. They also consume those minds physically -- as in they eat the brains. Without the nutrients they receive from intelligent brain matter, mind flayers will wither and die. Enslaved minds don't always provide the most satisfying meals, however, so they often head to the surface to raid more stimulating brains.

Brains play a huge role in Mind Flayer's culture and survival. Most Illithid communities center themselves around the Elder Brain they serve, nourishing their young tadpoles in the Elder Brain's tank, which is filled with nutrient rich brain matter and bodily organs.

Ceremorphosis

Because of their vast intellect, Mind Flayers have been known to experiment on their thralls by implanting other species with their tadpoles in a process known as ceremorphosis. Creating ceremorphs, as they are called, is often a gamble because finding compatible species isn't always easy. Attempting ceremorphosis with an incompatible creature often resulted in the death of the subject and the tadpole. A variety of mutated monsters have occurred as a result of these strange science experiments, including the Brainstealer Dragon, a mutated Beholder known as a Mindwitness and the Deep Gnome ceremorph known as a Mozgriken.

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