Slab Hammer is a uncommon Artifact — Equipment card from Battle for Zendikar (BFZ), collector number 227. Current market price: $0.11 (foil $0.56), TCGplayer market prices via Scryfall.
Whenever equipped creature attacks, you may return a land you control to its owner's hand. If you do, the creature gets +2/+2 until end of turn. Equip {2}