The Kingmaster by C. A. Doehrmann
The Hero of EllunonKyen is a talented swordsman with a heavy reputation on his shoulders. Shy and destitute, all he wants is to wander the wilderness the rest of his days—and to hide a powerful secret.
Until word arrives that his best friend, Finn, the Crown Prince, has been possessed by a sorcerer known as the Kingmaster. The royal family calls on Kyen to save him, but steel is useless against his dark and sentient magic.
Adeya is a princess doomed to an arranged marriage. Once celestial beings wielded the Three Powers at the command of her people. Now, they've fallen silent, and, with fiends running amok and her kingdom on the brink of ruin, she must marry… or find an arcangel who still answers.
Together they embark on a quest, following the rumors of a last summoner hiding his arcangel in an ancient forest. Fiends, dragons, and thieves can't compare to the Kingmaster as his black magic turns every friend they meet into an enemy. When his designs ensnare Adeya, Kyen must choose between saving his friends or releasing a secret that will endanger all the kingdoms of Ellunon.