Ulvenwald Mysteries is a uncommon Enchantment card from Double Masters (2XM), collector number 184. Current market price: $0.21 (foil $0.13), 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.