Demoralize is a common Instant card from Odyssey (ODY), collector number 184. Current market price: $0.19 (foil $0.64), TCGplayer market prices via Scryfall.
All creatures gain menace until end of turn. (They can't be blocked except by two or more creatures.) Threshold — If there are seven or more cards in your graveyard, creatures can't block this turn.