Bitterblossom is a mythic Kindred Enchantment — Faerie card from Ultimate Masters (UMA), collector number 85. Current market price: $33.97 (foil $40.08), TCGplayer market prices via Scryfall.
At the beginning of your upkeep, you lose 1 life and create a 1/1 black Faerie Rogue creature token with flying.