First Lord's Fury: Codex Alera, Book 6 - The C- Jim Butcher

The aging First Lord of Alera has fallen in battle. Yet his people must continue to resist an invading inhuman army. Desperate Alerans even pledge fealty to the Vord Queen to survive, turning the incredible power of Aleran furies back on their own people. And despite all efforts, the Alerans are being ground into dust and pushed to the farthest reaches of their own realm. However, Tavi has returned with vital insights from the Canim Blood Lands. He knows how to counter the Vord and, more importantly, believes human ingenuity can equal fury-born powers. Now events are rushing towards a last stand, where Tavi and the last Aleran legions must formulate a dangerous new strategy, together. For a civilisation is on the brink of extinction.