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The Citadel of the Black is a sprawling, partially-organic complex, made out of both black stone harder than steel and organic features, like jagged spines and bulbous domes, made of skin. It is several miles wide, and its highest spire is nearly a mile high.1
The dark lord of the Citadel of the Black is only known as Carsai the King, an enigmatic being constantly wreathed in smoke, with only flashes of his cloak and burning eyes visible. He often invites victims, worshippers of the Great Old Ones, and those that attract his attention from Golarion to reside in the Citadel of the Black.12
The Citadel of the Black is neutral ground between the Old Cults and the Dominion of the Black, with Carsai playing both sides. One of the few places in the solar system where worship of the Great Old Ones is not banned, the Citadel of the Black is home to those who seek their secrets, who accepted Carsai's invitation, or transported themselves there. They study at the Weeping Cathedral, a squamous temple containing copies and originals of blasphemous books about the Dark Tapestry, and work together as much as their insanity and paranoia would allow.13
Beneath the Citadel of the Black, the Dominion of the Black runs nightmarish fleshfarms. Within these fleshfarms are networks of hundreds of sensory creches, artifacts which allow the conscious minds of their occupants to voyage while their biological necessities do not have to be fulfilled. These networks absorb their thoughts and feed them to womb-vaults that create creatures modelled after their combined imaginations, which usually resemble creatures from the solar system.1
- Robert Brookes, Thurston Hillman, Brandon Hodge, Thomas M. Reid, and Mark Seifter. (2015). Occult Realms, p. 48. Paizo Inc. ISBN 978-1-60125-794-9
- Ethan Day-Jones, Jim Groves, Jonathan H. Keith, Andrew Romine, David N. Ross, and James L. Sutter. (2014). People of the Stars, p. 31. Paizo Inc. ISBN 978-1-60125-674-4
- James L. Sutter. (2012). Distant Worlds, p. 49. Paizo Publishing, LLC. ISBN 978-1-60125-403-0