The Last of the Renshai by Mickey Zucker Reichert

From the publisher (source: The Internet Book List):

The Wizards—Down through the centuries these four masters of magic have struggled to maintain the delicate balance of power in the troubled Northlands. But now the mortal world teeters on the brink of the long–foretold Great War, and not even the eternally conflicting sorceries of the Wizards may be enough to stave off the start of a battle which could—so legends say—herald the beginning of the dreaded final age for mortals, Wizards, and even the gods themselves...

The Renshai—They are the mightiest, most hated and feared of all warrior races. When their enemies band together in a surprise attack on their homeland, one Renshai will escape the genocidal ambush. He is a fighter destined to walk the pathways of prophecy, a lone warrior determined to keep the memory of his people alive and to claim his vengeance on the slayers of his race—and a master of destruction who—if he can survive in a world where the very name Renshai is a guaranteed sentence of death—may be doomed to become the Champion of the Great War...

This book is part of the "Renshai Trilogy" series.
Here are some other books from this series: