The new Baldur's Gate 3 demo at PAX East showcased an epic chase through the planes featuring one of Dungeons & Dragons' oldest horrors: the illithids. Officially nicknamed "mind flayers," these tentacle-faced psionic terrors have been sucking out the brains of adventurers in D&D since its inception, and they've been a fan favorite ever since. So who (or what) are the mind flayers, what are the madness-inducing details of their life-cycle and who thinks up a race of brain-eating mad scientists in the first place?

The original idea for these tentacled nightmares goes all the way back to the beginning of the game and creator Gary Gygax himself. According to Gygax, he was immediately inspired to create the illithid after spotting a book cover for The Burrowers Beneath by Brian Lumley -- a novel that lives squarely inside the cosmic horror shared fictional universe known as the Cthulhu Mythos. In Burrowers, unstoppable tentacled monstrosities known as chthonians plot from beneath the earth to rise up and overthrow the surface. Sound familiar? Something about the writhing tentacled face of the chthonian on the cover inspired Gygax to build his own race of intelligent tentacled horrors, and this theme of cosmic alien horror persists in the lore of the mind flayer to this day.

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Each individual illithid is tall, thin and sexless but able to lay a clutch of eggs at least once in their long lives from which baby illithid tadpoles hatch. The first 10 years of life for the nascent monsters are brutal -- the tadpoles are put into a massive elder brain tank where they are fed brains, but not enough to prevent them from needing to engage in cannibalism and consuming rival tadpoles.

What's worse, the elder brain itself feeds exclusively on tadpoles. Those that are cunning or lucky enough to survive to maturity are then put through the ceremony of ceremorphosis. This horrifying ritual begins when a tadpole is implanted into a humanoid victim. Eventually, it devours the host's brain, takes its place and merges with its body to transform it into an adult illithid. From that moment on, the host is gone, replaced by a capable, four-tentacled terror.

The majority of illithid enclaves are led politically and militarily by an enormous tentacled brain in a vat. The elder brain serves as the biological database of the community's memory, technology and intelligence. It represents the ultimate end to each illithid's life, as, upon reaching the end of their lifespan, illithids sacrifice themselves by merging with the elder brain, strengthening its mind and power. However, most illithids are unaware that their personality and consciousness are totally lost when joining with the elder brain, just as the illithid's hosts lost theirs during ceremorphosis.

New illithids colonies are rare and only come about when a tadpole mutates its host into an especially powerful form known as an ulitharid. These super-illithids are superior to regular mind flayers in every sense, even having extra face tentacles. Most importantly, they are free from the elder brain's psionic control. Elder brains are forced to accept these upstarts directly, and, if the ulitharid isn't assassinated, it breaks off with a small group of followers to establish a new colony. Eventually, the ulitharid transforms into a new elder brain, and this disgusting cycle begins anew.

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Like other parasitic monsters, illithids must regularly consume the living to survive. Like how vampires must drink the lifeblood of mortals, illithids must consume the brains of living humanoids. To get their prey, illithids have an arsenal of potent magic, technological devices and personal psionic powers to use to mind-blast all but the most prepared adventuring parties into submission. While individually vulnerable, the illithid's vast intellect usually prevents them from encountering danger in most circumstances.

While classic vampires take inspiration from flaws such as aristocratic greed or uncontrollable lust, illithids represent unknowable alien urges made even more terrifying by their obfuscation. Illithids need to research emotions to understand them, but they are smarter than most living creatures. This combination of intelligence and alien intent makes for a wonderful campaign antagonist that is unique from other monsters.

A lot that can go wrong (or strange) when illithids create things. Ceremorphosis is an ill-understood horror scene by design, so applying the ritual to other monsters has become a trope of its own. For example, if a mature tadpole does not undergo ceremorphosis, it just keeps growing, eventually becoming a massive worm-like creature. Much like Alien's xenomorph, the illithid's need for and choice of hosts can have a profound effect on the result. Most humanoids result in the creation of a normal illithids, but what if one selected something crazy like the cacodemon-esque beholders or a centuries-old dragon? Combining illithids with other creatures provides the opportunity for game masters to unleash unique horrors into their campaigns by slapping tentacles and a psionic powerset on almost any monster.

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So where did these monsters originate within D&D's lore? One terrifying possibility is that the illithid race itself comes from the far-future. This mind flayer empire, built upon the subjugation of other races that existed in that time, is said to have dwarfed everything that has been built since. Its influence was so great that even the demons of the Abyss and devils of the Nine Hells feared them. It was in this future that disaster struck -- some unstoppable adversary or calamity hit the empire so hard that they had to sacrifice most of their elder brains and blow-up time to escape it. These super-advanced illithids fled their own time to land thousands of years in the past and immediately began to rebuild, taking slaves of a race called the Gith (a playable race in Baldur's Gate 3).

At some point, however, a critical mass of Gith slaves grew resistant to the illithid's control and rebelled. With their main source of food and labor throwing down their tentacled oppressors and trying to kill them, the already weakened illithid empire crumbled, losing much of its advanced technology in the process. A time of reckoning began, and the monstrous illithids were nearly hunted to extinction, forced to hide deep beneath the earth in the Underdark where the Gith would not follow. Despite this setback, to the elder brains, all is written and the future is a known factor. All they need to do is wait with the power of thousands of years of hindsight for the chance to swing history to their favor once again.

Mind flayers are among the creepiest and most fun villains that can be included in a D&D game. Whether you want a sinister mastermind to control other monsters from behind the scenes, or an entire campaign flavored with Call of Cthulhu style cosmic horror, illithids make for gut-churning terror on the tabletop in the best of ways. Now armed with knowledge of these aberrations, hopefully you can keep your head as they crash into Baldur's Gate 3.

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