Murasa is a common Plane — Zendikar card from Planechase Anthology Planes (OPCA), collector number 53. Current market price: $4.01, TCGplayer market prices via Scryfall.
Whenever a nontoken creature enters, its controller may search their library for a basic land card, put it onto the battlefield tapped, then shuffle. Whenever chaos ensues, target land becomes a 4/4 creature that's still a land.