Child of Flame by Kate Elliott

Child of Flame takes us far beyond the borders of the war-torn kingdoms of Wendar and Varre as Alain is drawn into the heart of an ancient conflict between humankind and their dread enemy, the Cursed Ones; Liath faces her most difficult trial in a land of exile; and Sanglant struggles to reach Henry with a warning about the conspiracy of sorcerers who have sworn to put an end to the Aoi -- no matter how much destruction may be unleashed by their workings of magic....