Act of Treason is a common Sorcery card from Khans of Tarkir (KTK), collector number 95. Current market price: $0.13 (foil $0.37), TCGplayer market prices via Scryfall.
Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)