The Boulder, Ready to Rumble is a uncommon Legendary Creature — Human Warrior Performer card from Avatar: The Last Airbender (TLA), collector number 168. Current market price: $0.21 (foil $0.35), TCGplayer market prices via Scryfall.
Whenever The Boulder attacks, earthbend X, where X is the number of creatures you control with power 4 or greater. (Target land you control becomes a 0/0 creature with haste that's still a land. Put X +1/+1 counters on it. When it dies or is exiled, return it to the battlefield tapped.)