The Dark Sect
A secret organisation dedicated to unleashing the Old Dark God Nylonathatep, the Laddering Horror so that it could destroy the Disc. The fact that this would kill them too did not bother them. To say that the members of the Dark Sect were highly unhinged would be a slander on decent hard working madmen. The sort of people who try to summon the horrors from the Dungeon Dimensions are the sort of people who leave a bit of string to guard their house and shout abuse at their walls.
The Dark Sect once succeed in raised Nylonathatep from its prison in the sunken city of Leshp where it had been trapped with Drunken Cthubopalulu. It was summoned by an Octogram of Murders - eight ritualistic deaths around the Circle Sea, centred on Leshp. Fortunately for all concerned Nylonathatep was defeated before it had gone to far, banished by the Golden Tsortese Falchion of Errata.
The Dark Sect vanished and was believed to have died out and while people speculated as to the final resting places of the Laddering Horror, the few books detailing this event gave no clue.