The Wings of Wrath — C.S. Friedman

At the end of her bestselling Coldfire trilogy, C.S. Friedman challenged readers to imagine what a world would be like if sorcery required the ultimate sacrifice...that of life itself. Now, in the Magister trilogy, she introduces us to a terrifying world in which the fuel for sorcery is the very fire of the human spirit, and those who hunger for magical power must pay for it with their lives.

Against all odds, the young peasant woman Kamala has proven strong and determined enough to become a Magister -- the most powerful of all sorcerers. Only the Magisters can draw on the power of a human soul without dying for it, and they guard this fearsome secret above all else. But now this shadowy brotherhood hunts Kamala for killing one of its own, and her only hope of survival may lie in fleeing north toward the magical barrier called the Wrath, that even the Magisters fear. This ancient and mysterious fortification was created to protect humanity from demonic creatures who once nearly obliterated the human species. But the Wrath is now weakening, and those who are sworn to protect the human lands must uncover the reality that lies at the heart of ancient legends as they struggle to defeat an enemy that once brought mankind to the very brink of destruction.