Treetop Ambusher is a common Creature — Elf Berserker card from Modern Horizons (MH1), collector number 186. Current market price: $0.16 (foil $0.19), TCGplayer market prices via Scryfall.
Dash {1}{G} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.) Whenever this creature attacks, target creature you control gets +1/+1 until end of turn.