Dunno, this shard right now as it stands seems to be a little weak, after all, if you deal more than 2-3 damage/turn against a non-healing opponent this shard loses its effect. IMO, to buff it and to remove some of the "situationality" of this card, I think it would be a great addition if the maxHP reduced from the opponent would in turn raise the user's maxHP. It would fit very nicely in many decks as there are plenty of healing cards associated with Darkness that could take advantage of increases in maxHP- just a thought!