Spirits of Light and Shadow — India Drummond

Book 1 of The Gods of Talmor: When the most powerful senator in Talmor's second-largest city is cursed with dark magic, the other legislators secretly turn to his estranged son Korbin as a last, desperate chance to find a cure. With the assistance of a refugee schooled in the foreign magic of the One, Korbin seeks to help his father-and find redemption. But an ancient Spirit of Shadow sets the pair in her sights, corrupting their every hope into despair... and turning their quest for a cure into a fight for survival.