Princeps' Fury : Book Five of the Codex Alera

After achieving a fragile alliance with the savage Canim, Alera's oldest foes, Tavi of Calderon--now the Princeps Gaius Octavian and heir to the throne--is confronted by an invasion of the Vord, which forces the Aleran legions and Canim warriors into a desperate battle for survival against a dreaded mutual enemy. Reprint.