OP asks how we could possibly kill Garrosh, who's decided to exploit the 'heart' of an old god. We've already defeated enemies who could be considered far worse. Yes a lot of people are arguing that ''WE DIDNT DO IT, MAJOR LORE HEROES DID'' Fact is, OP is asking ''how we could possibly do it'' and there are plenty of ways it's possible and we've seen several of them in action