Herd Mistress. In Deception's Shadow, #2

Magic. It turned Sorsha Stonemantle's world on its head. Yet she can't hate magic for without it Shadowdancer, the Santhyrian ambassador, would never have come into her life. In the days following their first meeting, Sorsha knows Shadowdancer completes her soul. There's only one problem. Any relationship beyond friendship is impossible. From the moment Shadowdancer encountered Sorsha, he knew she was a Herd Mistress-a rare worker of magic, key to the Santhyrian nation's survival.
His first obligation is to protect her and bring her back to the safety of the herd, but when Sorsha is threatened by Lord Master Trensler and his priesthood, they soon discover Trensler serves a darker master, one willing to devour all magic until the world dies. And that evil wants Shadowdancer and Sorsha. When a second ambush set by Trensler cripples Sorsha's magic and traps Shadowdancer in the form of a man, they barely escape with their lives.
Unwilling to allow her lack of magic to rule her life, Sorsha sets out to teach Shadowdancer that being human isn't a curse. The proud Santhyrian stubbornly tries to push Sorsha away, but when they are endangered once again, they realize they must work together to find a way to heal themselves. If they fail, Trensler's master will devour first them and then everything else Sorsha and Shadowdancer ever loved.