Collective Nightmare is a uncommon Instant card from March of the Machine (MOM), collector number 95. Current market price: $0.17 (foil $0.04), TCGplayer market prices via Scryfall.
Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.) Target creature gets -3/-3 until end of turn.