The divine seat of power for which the newly unsponsored Eris is named a prime contender.
Eris's system description ends with a line that reframes her entire visit: Eris is a prime contender for the Ascendent Throne. It follows directly from her unique status this season, having lost her sponsor and become unable to be re-sponsored, escaping The War Mages and letting her true purpose surface.
That ambition explains her recruitment of Carl, her offer to make him Champion as Nekhebit had just made Princess Donut, and her insistence that he kill Taranis Apito, Emberus, and Hellik. Her freely-given intelligence about Paca and the Gate of the Feral Gods serves the same end.
The prize Eris is positioning herself and Carl to win.