Okay, I think this could work. You are saying that on a fumble you give a +2 to hit self or fellow party members on the next attack? That sounds reasonable. And Leif thinks I should make it a permanent +2 to hit self or fellow party members? I guess that would come into play on fumbles or when magic effects like confusion or charm are in play? There could be some of those in the Tomb. Walking Dad says +1 is enough, but really, I don't want you feel cheated...