I like some of the suggestions people have been throwing around. Slight potency increase to Bloodspiller. Reduce or remove mp cost of Dark Passenger. Right? It needed more of a dps gain than it got to make up for lack of utility. Well you could give it utility instead, like Sole Survivor also places a vulnerability up debuff on the target to boost raid dps. If that's too much... I guess an aoe shield mitigation to match the other two tanks?