Epic Experiment is a mythic Sorcery card from Return to Ravnica (RTR), collector number 159. Current market price: $0.45 (foil $2.55), TCGplayer market prices via Scryfall.
Exile the top X cards of your library. You may cast instant and sorcery spells with mana value X or less from among them without paying their mana costs. Then put all cards exiled this way that weren't cast into your graveyard.