Prohibit is a common Instant card from Modern Horizons (MH1), collector number 64. Current market price: $0.19 (foil $0.47), TCGplayer market prices via Scryfall.
Kicker {2} (You may pay an additional {2} as you cast this spell.) Counter target spell if its mana value is 2 or less. If this spell was kicked, counter that spell if its mana value is 4 or less instead.