Splitting the Powerstone is a uncommon Sorcery card from The Brothers' War (BRO), collector number 63. Current market price: $0.11 (foil $0.21), TCGplayer market prices via Scryfall.
As an additional cost to cast this spell, sacrifice an artifact. Create two tapped Powerstone tokens. If the sacrificed artifact was legendary, draw a card. (The tokens are artifacts with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")