The Great Aerie is a common Plane — Tarkir card from March of the Machine Commander (MOC), collector number 53. Current market price: $1.36, TCGplayer market prices via Scryfall.
When you planeswalk to The Great Aerie and at the beginning of your upkeep, bolster 3. (Choose a creature with the least toughness among creatures you control and put three +1/+1 counters on it.) Whenever chaos ensues, choose up to one target creature you control and up to one target creature an opponent controls. Each of those creatures deals damage equal to its toughness to the other.