Baleful Eidolon is a common Enchantment Creature — Spirit card from Theros (THS), collector number 78. Current market price: $0.06 (foil $0.46), 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.) Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.) Enchanted creature gets +1/+1 and has deathtouch.