Ob Nixilis, Captive Kingpin

Flying, trample
Whenever one or more opponents each lose
exactly 1 life, put a +1/+1 counter on Ob
Nixilis, Captive Kingpin. Exile the top card
of your library. Until your next end step, you
may play that card.

"I know my mind is changing...
but I'm already gone too far to know what to do." —Simon Petrikov