Act on Impulse is a uncommon Sorcery card from The List (PLST), collector number M15-126. Current market price: $0.26, TCGplayer market prices via Scryfall.
Exile the top three cards of your library. Until end of turn, you may play those cards. (If you cast a spell this way, you still pay its costs. You can play a land this way only if you have an available land play remaining.)