Ulvenwald Mysteries' second ability triggers, creating a 1/1 Human Soldier creature token that enters the battlefield with at least one +1/+1 counter due to Bloodspore Thrinax.
Resolve the Clue ability from step 1, causing you to draw a card.
Activate Ashnod's Altar by sacrificing the Human Soldier, adding CC.
The Human Soldier leaves the battlefield, triggering Angelic Sleuth, creating a Clue token.