Ulvenwald Mysteries is a uncommon Enchantment card from Shadows over Innistrad (SOI), collector number 236. Current market price: $0.07 (foil $0.42), TCGplayer market prices via Scryfall.
Whenever a nontoken creature you control dies, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.") Whenever you sacrifice a Clue, create a 1/1 white Human Soldier creature token.