Hero in the Shadows (Drenai Series)

The ruined city of Kuan Hador reeks of dark mystery. Shunned by brigands and merchants alike, it is home to fearsome wild things and legends that freeze the blood--tales that speak of slavering white beasts, locked behind a powerful wall of spells, who possess an insatiable appetite for death. Millennia have passed since they were bound, and the spell of imprisonment has begun to fade. Soon the foul minions will be free to wreak a horrible vengeance against all that lives.

But no army waits ...