Avengers Assemble! is a mythic Enchantment card from Marvel Super Heroes (MSH), collector number 341. Current market price: $5.26 (foil $8.98), TCGplayer market prices via Scryfall.
Flash Heroes you control get +2/+2. At the beginning of each end step, if you attacked with a Hero this turn or a Hero entered the battlefield under your control this turn, draw a card.