Emperor Mage - Tamora Pierce

Daine must confront a powerful leader in this third book of the Immortals series, featuring an updated cover for longtime fans and fresh converts alike, and including an all-new afterword from Tamora Pierce.
When Daine is sent to Carthak as part of a Tortallan peace delegation, she finds herself in the middle of a sticky political situation. She doesn't like the Carthaki practice of keeping slaves, but it's not her place to say anything--she's only there to heal the emperor's birds. Her worries only expand once she learns that her own power has grown in a dark and mysterious way.
As the peace talks stall, Daine puzzles over Carthak's two-faced Emperor Ozorne. How can he be so caring with his birds, and so cruel to his people? Daine is sure he's planning something--a terrible, power-hungry scheme. And she knows that she must fight this powerful Emperor Mage; the life of her beloved teacher is at risk.