My Crushing Masterstroke is a common Scheme card from Duskmourn: House of Horror Commander (DSC), collector number 342. Current market price: $0.38, TCGplayer market prices via Scryfall.
When you set this scheme in motion, gain control of all nonland permanents your opponents control until end of turn. Untap those permanents. They gain haste until end of turn. Each of them attacks its owner this turn if able.