Aboleths are a race of malevolent, eel-like aberrations with potent psionic abilities and a much more fearsome ability: the capacity to secrete a viscous gray fluid, much like mucus, that brings about a terrible transformation in air-breathing creatures so unfortunate as to be caught in the fluid. The skin of the victim was transformed into a membrane that allowed it to breathe in water, and changed the creature’s consciousness to that of a mindless servant. This allowed aboleths to keep slaves, known as aboleth servitors, which they dominated and kept captive through their mind. Only the most powerful aboleths could do this, however, completing the process through a powerful ritual.