Doesn't matter frankly, particularly given the state of tanks. Marauder/warrior have had lifesteal and hp generation since inception, so trying to steal that for dark knight doesn't really do anything but further make it a warrior clone. A solution would be putting nascent/bw back on percent of damage dealt, having abyssal drain as x potency on hit with an mp cost, as a sort of halfway house between clemency (potency) and warrior (actually doing something useful). Since we can give it an arbitrary 3000mp cost, it could either interact with tbn breaks, an interesting mp generating button - sticking something onto quietus perhaps - or just relying on regular mp generation, which is 200/tick before blood weapon. I'd rather the latter option wasn't taken because that's 3 stacks with ~45s between uses as a worst case scenario, but could be worse.