Dragon Shadow is a common Enchantment — Aura card from Scourge (SCG), collector number 65. Current market price: $0.30 (foil $7.02), TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature gets +1/+0 and has fear. (It can't be blocked except by artifact creatures and/or black creatures.) When a creature with mana value 6 or greater enters, you may return this card from your graveyard to the battlefield attached to that creature.