Halcyon Glaze is a uncommon Enchantment card from Ravnica: City of Guilds (RAV), collector number 54. Current market price: $0.14 (foil $0.37), TCGplayer market prices via Scryfall.
Whenever you cast a creature spell, this enchantment becomes a 4/4 Illusion creature with flying in addition to its other types until end of turn.