Osyluth

An osyluth is an unparalleled inquisitor that revels in the sadism and torture for which Hell is so well known. These devils' charge is to seek out heresies, both among mortals and among other fiends-a commandment they uphold with unwavering fervor. They spawn within the Styx-fed swamps of Hell's fifth layer, Stygia; where heresies and the souls of heretics stagnate, osyluths eventually rise. In the remote corners of that same layer of Hell, they build massive, calcified hives where they perform their vile interrogations and perfect their torturous arts upon lesser devils and petitioners alike.

Each type of devil plays a particular role in Hell's bureaucracies and hierarchies, though some have far more specialized functions than others