Wild Onslaught is a uncommon Instant card from Dominaria (DOM), collector number 188. Current market price: $0.08 (foil $0.28), TCGplayer market prices via Scryfall.
Kicker {4} (You may pay an additional {4} as you cast this spell.) Put a +1/+1 counter on each creature you control. If this spell was kicked, put two +1/+1 counters on each creature you control instead.