Demon of the Yawning Pit

Trample
Pact - Sacrifice a land or tap Demon of the
Yawning Pit and it deals 9 damage to you. (At the beginning of your upkeep, pay this permanent's pact
cost. If you can't, sacrifice this permanent.)
Creatures your opponents control get -X/-X,
where X is half the number of land cards in your graveyard, rounded down.