Midsummer Revel is a rare Enchantment card from Urza's Saga (USG), collector number 268. Current market price: $0.56, TCGplayer market prices via Scryfall.
At the beginning of your upkeep, you may put a verse counter on this enchantment. {G}, Sacrifice this enchantment: Create X 3/3 green Beast creature tokens, where X is the number of verse counters on this enchantment.