Hedron Fields of Agadeem is a common Plane — Zendikar card from Planechase 2012 Planes (OPC2), collector number 19. Current market price: $2.63, TCGplayer market prices via Scryfall.
Creatures with power 7 or greater can't attack or block. Whenever chaos ensues, create a 7/7 colorless Eldrazi creature token with annihilator 1. (Whenever it attacks, defending player sacrifices a permanent of their choice.)