Wayward Conglomerate

Whenever you put a +1/+1 counter on a creature
you control, you may put a -1/-1 counter on a
creature an opponent controls. Whenever a creature leaves the battlefield, its controller loses life
equal to the amount of -1/-1 counters on it.
"Oh forgive me, it seems I have underestimated your resiliance, I promise you won't last much longer."