Hypnotic Siren is a rare Enchantment Creature — Siren card from Journey into Nyx (JOU), collector number 42. Current market price: $0.29 (foil $1.38), TCGplayer market prices via Scryfall.
Bestow {5}{U}{U} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached.) Flying You control enchanted creature. Enchanted creature gets +1/+1 and has flying.