The Witchslayer — A.K. Mulford

Renwick Vostemur spends his winters training blue witches with his uncle in the Northern Court. But as Renwick proves himself worthy of the nickname Witchslayer, he struggles to keep his secrets from slipping out of his control. Under his uncle's scrutiny, will he survive another winter in the blue witch fortress? This is the third novella in the Okrith Novellas series. Each novella can be read as a standalone.