Nyxborn Eidolon is a common Enchantment Creature — Spirit card from Born of the Gods (BNG), collector number 78. Current market price: $0.10 (foil $0.45), TCGplayer market prices via Scryfall.
Bestow {4}{B} (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.) Enchanted creature gets +2/+1.