The King's Glory by Karen Michalson

The King's Glory is the third book in Karen Michalson's Enemy Glory trilogy. Hecate orders Llewelyn to restore a now-damaged world to its pre-damaged state without violating his evil alignment. If he fails, he will suffer unspeakable torture upon death. Forever. Which could happen at any time, seeing that everybody he's ever had contact with—including other evil clerics—are trying to kill him. Unwillingly aligned to evil, facing eternal torture should he die without fulfilling Hecate's mandate, he must justify the world to the gods.