Eel Umbra is a common Enchantment — Aura card from Rise of the Eldrazi (ROE), collector number 65. Current market price: $0.14 (foil $0.81), TCGplayer market prices via Scryfall.
Flash (You may cast this spell any time you could cast an instant.) Enchant creature Enchanted creature gets +1/+1. Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)