If one were to get into varrock it wouldn't last long, people would be lining up to place blows on that glitch so they could be the one to take it down. Anyway, the ability for revanents to attack is based on wilderness level, I have walked passed revs to high/low to attack me and they have completly ignored me so it probably wouldnt be able to do any damage anyway. As for drop, the best you can get from them is a dragon dagger or a glory. There drops arn't worth the effort to kill them.