Brago's Favor is a common Conspiracy card from Conspiracy (CNS), collector number 3. Current market price: $0.16 (foil $0.28), TCGplayer market prices via Scryfall.
Hidden agenda (Start the game with this conspiracy face down in the command zone and secretly choose a card name. You may turn this conspiracy face up any time and reveal that name.) Spells with the chosen name you cast cost {1} less to cast.