Snake Umbra is a common Enchantment — Aura card from Planechase Anthology (PCA), collector number 78. Current market price: $1.01, TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature gets +1/+1 and has "Whenever this creature deals damage to an opponent, you may draw a card." Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)