Smoke Shroud is a common Enchantment — Aura card from Modern Horizons (MH1), collector number 69. Current market price: $0.25 (foil $5.11), TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature gets +1/+1 and has flying. When a Ninja you control enters, you may return this card from your graveyard to the battlefield attached to that creature.