summoning of Cthulhu

whenever a creature an opponent controls leaves
the battlefield, put a soul counter on summoning
of Cthulhu. when summoning of Cthulhu has 3
or more soul counters on it, target player
discards 3 cards, then search your library for a
card called Cthulhu
it will come. and it will tear apart your feeble mind for attempting to defy its will.
- samul, the voice of Cthulhu