Ob Nixilis, Fortune's Scourge

Flying, trample
Whenever one or more opponents each lose
exactly 1 life, put a +1/+1 counter on Ob Nixilis,
Exile the top card of your library. Until your
next end step, you may play that card.
Whenever a creature you control dies, if it had
one or more counters on it, you may put that
many counters on target creature.