Rakdos, Lord of Ravnica

Trample, Menace
Other Devils, Imps and Tieflings gains +2/+0 and Trample.
Rakdos, Lord of Ravnica enters the battlefield
with it's power equal to X.
Whenever Rakdos, Lord of Ravnica attacks,
exile cards from on top of your library until you reveal a demon, devil, imp or tiefling with a converted mana cost less than or equal to Rakdos, Lord of Ravnica's power. Put that card on the battlefield. You can cast the cards exiled with it this turn.