Chris Bunch 
Shadow Warrior 

The Great War with the vile Al’ar was all but forgotten, the last alien resistance eliminated ten years ago. However, war hero Joshua Wolfe cannot forget. Friend, prisoner then destroyer of the Al’ar, they called him Shadow Warrior — master of the Al’ar killing arts. He alone knew the conflict was far from over.Originally published in three separate volumes in the US, SHADOW WARRIOR is the first UK publication for this gripping SF series.