The Librarian. A mysterious woman that lives on an alternate dimension full of all kinds of books she has read. She is so powerful that one time a god tried to consume reality was stopped by her. Chernobog had his body destroyed, almost killing him. The Librarian is the only being in the setting that has been able to do that.
Novels
Cult of Corruption: The Summoning
The final confrontation. Bo being able to stop Nergal from completely winning at the end of the novel by casting a cleansing spell that cures everyone corrupted by the god and his followers. Bonus points from doing so while being almost completely corrupted into his service thanks to Karen and his feelings towards the woman.
Slugs and Bugs: Invasion
Justine and Jen surviving the invasion inside the Erebus building, considering it ends up full of Infectulons and transformed people.
Justine escaping the Over-Master by freezing time with her psychic powers.
