The Raven's Shadow - The Wild Hunt Book Three

Sometimes those with the greatest potential must withstand the hardest blows. Fate, it seems, has nothing kind in store for Gair. First his lover and now his mentor have been killed - the first by the dangerous, ambitious Savin, the second in a revolutionary uprising. Alone, and with even his magical abilities betraying him, he has only one goal left: revenge. Far to the north, if Teia has one goal it is survival.
Attempting to cross a high mountain pass in the teeth of winter is an act of desperation, but the message she carries cannot wait for spring. An invasion force is gathering behind her, and only an ancient order of knights can hold them back. The danger is real, there are enemies in the shadows, and time is running out ...