Echoing Boon is a uncommon Conspiracy card from Conspiracy: Take the Crown (CN2), collector number 3. Current market price: $0.09 (foil $0.71), 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.) Whenever you cast an instant or sorcery spell, if it targets a creature you control with the chosen name, you may copy that spell and may choose new targets for the copy.