Beast Master Rey Endrigo is a beast man battle slave

Leon Clawmaen is a beast man battle slave being used as a shock troop with other slaves. One day on a battle field Rey and his fellows are being attacked and slaughtered by enemy soldiers and slaves when Rey realizes that among his allies he sees no humans or elves fighting/ dying. He then turns to see that the human army is fleeing leaving Rey and his men to die. Upon this realization Rey is stabbed through the heart and in his dying breath curses humanity and prays to the Gods for vengeance. And as luck would have it a God answers his prayers.