Spawnsire of Ulamog - Rise of the Eldrazi (ROE)

Annihilator 1 (Whenever this creature attacks, defending player sacrifices a permanent.)
4: Put two 0/1 colorless Eldrazi Spawn tokens onto the battlefield. They have "Sacrifice this creature: Add 1 to your mana pool."
20: Cast any number of Eldrazi cards you own from outside the game without paying their mana costs.