Holly Lisle: The Courage of Falcons [2002] paperback

Kait Galweigh, her Sabir lover Ry and his cousin Ian have captured the Mirror of Souls, an artefact that can confer immortality, but only at huge cost to the innocents whose souls are used to feed it. But while Kait and her friends are battling the ages-old evil of the Mirror, her cousin Danya, raped and Scarred, is being groomed for godhead, gathering together a mighty army of the Scarred, ready to invade and conquer the Rich Lands. COURAGE OF FALCONS, like the first two books in the sequence, is a masterful fantasy with well-realised characters, a cracking plot and a villain who exudes evil from every pore.