Enchantment
Whenever a nontoken creature you control dies, investigate. (Create a Clue token. It's an artifact with "

, Sacrifice this token: Draw a card.")
Whenever you sacrifice a Clue, create a 1/1 white Human Soldier creature token.
If a nontoken creature dies at the same time as Ulvenwald Mysteries leaves the battlefield, the first ability triggers. Similarly, if Ulvenwald Mysteries isn’t a token and has become a creature, it dying will cause its own first ability to trigger.