Curse of Strahd
Illithids are super-intelligent, humanoid creatures of great (and lawful) evil. Illithids have an octopus-like head with four tentacles around a lamprey-like mouth that they use to penetrate to the brain and draw it forth for food as they require the brains of sentient creatures as part of their diet. An illithid who snares a living creature in all four of its tentacles can extract and devour its living brain. Their eyes are pale white, and they can see perfectly well in both darkness and light. Their sense of hearing is slightly poorer than a human’s; they have difficulty distinguishing between several sounds mixed together, yet they are good at discerning from what direction sounds came from. Their skin is purplish blue to gray-green and covered in mucus, and is very sensitive to sunlight. They loathe sunlight, though it does not actually harm them.
It is whispered that in advanced Illithid societies, which have made their civilization far under the world above, the discovery of eldritch arcane powers, coupled with necro-organic science have produced a way for Illithid to farm and extract the nutrients of human brain tissue without the need for hunting their prey….