Medusae

Psychic hemorrhage incoming to the designated target.

Medusae are weird creatures of the Webway and no, they aren't the mythical snake ladies either. They often find themselves as servants within an Archon's court and are quite sought after by the denizens of the Dark City of Commorragh. Medusae are highly empathic parasites that appear as a collection of brains and spinal cords that are stacked on top of one another. These creatures seemingly float across the ether like jellyfish where they feed on the dreams, as well as nightmares, of sentient beings.

They can also latch upon a living host, allowing them to feed upon the emotions of their host directly and through this process, provide the power they require to manifest in realspace, thus becoming hybrid creatures of both the material world and the Immaterium. Usually the host ends up mutating to have one gigantic eye to shoot out their psychic mind bullets at their enemies. Of an entire race full of psychic nulls, the Medusae are one of the few Dark Eldar troops that can be fully psychic and the DE use them to their full advantage.

In combat, their empathic abilities are weaponised: a simple gaze from a Medusae can lead to instant emotional hemorrhaging by exposing their victims to raw anguish, potentially putting them into a coma from which there is no recovery. If it's an untrained Psyker, the Medusae would send them spazzing out like they're having the psychic equivalent of a stroke. In addition, they are also able to absorb extreme sensations, which are highly prized in Dark Eldar society. The brain fruit of the Medusae are capable of being consumed and allow an individual to re-experience the vivid and anarchic emotions of a raid all over again.... which is just fucking WEIRD even by the fucked up society of Commorragh. One novel has Vect sampling some Medusae brain fruit and is even able to get visual recollections of the experiences someone once had.