I'm a little in the dark on vengeance, I just came back to tanking this patch. I understand that when you take an unmitigated melee or ranged attack you gain 1.5% (I think) of that hit as attack power. I just don't understand when it scales better or what happens with it for example Thok, I hear of warriors getting 500k+ shields and 1.5m crit hits with shield slam.