Cult of the Yellow Sign

Little is known of this cult outside the Arcane Collegium—though perhaps some hint exists in the records kept at the Blue House and the Spyglass Guild. The cult of the Yellow Sign is one of alien magic and power granted to those initiates to a mystery tied somehow to the wellsprings of star and shadow magic. The masters of the Collegium say little about it, though they look worried when the subject comes up. What is known is the Cult of the Yellow Sign originates in the East. It is tied to the worship of Khors and involves the imminent return of a messiah or herald of some great power. This herald is sometimes called Hallisar or sometimes the Shining One, and he will speak directly to the minds of those who grant him obeisance and worship.
What Hallisar wants is unclear; a “pure land” and a “great cleansing” are both popular images in the repetitive, mind-numbing chants and screeds of his followers. His cultists seem to have some mastery over space and time, appearing and disappearing within the city at will, and no shrine to the Yellow Sign has ever been found.
The clockwork mages are experimenting to see if they might isolate some clue to Hallisar’s origins or determine any weaknesses of the cult, so far without success.