The other day I was thumbing through Vaults of the Weaver the Dave Hargrave's module collection & these modules have within them details about the Cult of Cthulhu on Arduin. These cults operate underground.
|Emperor's Choice does some excellent reprints of Dave Hargrave's old school materials
These cults operate with their own twisted nightmare agendas & they operate with impunity on Arduin. These secret cults have operated for thousands of years & they deal with dungeon monster NPC's. Cults such as the mythos maintain these various dungeons across Arduin. And when a godbound has appeared these cults go into overdrive. Godbound make excellent sacrifices to the mythos parasite gods.
And what does any of this have to do with Cha'alt?! Let's put this on point, the black pyramid calls these cults to itself on Cha'alt from across dimensions. The dungeons of Cha'alt have been created in the massive wars that once ravaged the sands of the planet. Cha'alt marks time until the great Old Ones become far more active. Could the black pyramid have its own unearthly agenda? Absolutely it could!
The black pyramids have their own agendas & perhaps the godbound are seen as nothing more then spiritual batteries. Spiritual batteries that could awaken the Great Old Ones before the stars come right!?! There are gigantic monsters that stalk across the wastelands of Arduin but are these horrors under the control of the gods of Chaos. These gods of Chaos & Lovecraftian horror often smuggle these monsters to a wide variety of worlds including Greyhawk. Crossing over from Arduin to Greyhawk is as simple as finding a portal in a dungeon on Arduin & stepping into Greyhawk. This is something that Hargrave makes really clear within the 'Arduin Grimoire Trilogy' book & a subject that carried over unto his section on his own version of the multiverse.
The breeding point for these horrors?! The black pyramids & their dungeons on Cha'alt! This profane location & planet is the perfect breeding point for monsters & demons beyond the ken of men!