Revenge to Redemption oleh S. B. Sebrick

Asher sets out to punish King Geladon for taking the innocent life of his dear friend, Jasmine. Only a towering fortress, half-animal guards, Geladon's own magic and Jasmine's moral teachings against revenge stand in his way.

Getting to Geladon will push him to the limits of his training. What he finds there will exceed his wildest dreams. It may also require the ultimate sacrifice.