Spawnsire of Ulamog is a rare Creature — Eldrazi card from Rise of the Eldrazi (ROE), collector number 11. Current market price: $9.35 (foil $33.69), TCGplayer market prices via Scryfall.
Annihilator 1 (Whenever this creature attacks, defending player sacrifices a permanent of their choice.) {4}: Create two 0/1 colorless Eldrazi Spawn creature tokens. They have "Sacrifice this token: Add {C}." {20}: Cast any number of Eldrazi spells from among cards you own outside the game without paying their mana costs.