Bloodwitch by Susan Dennard

Fans of Susan Dennard's Witchlands series have fallen in love with the Bloodwitch Aeduan. And now, finally, comes his story.

High in a snowy mountain range, a monastery that holds more than just faith clings to the side of a cliff. Below, thwarted by a lake, a bloodthirsty horde of raiders await the coming of winter and the frozen path to destroy the sanctuary and its secrets.

The Bloodwitch Aeduan has teamed up with the Threadwitch Iseult and the magical girl Owl to stop the destruction. But to do so, he must confront his own father, and his past.