Thought-Stalker Warlock is a uncommon Creature — Lizard Warlock card from Bloomburrow (BLB), collector number 118. Current market price: $0.23 (foil $0.28), TCGplayer market prices via Scryfall.
Menace (This creature can't be blocked except by two or more creatures.) When this creature enters, choose target opponent. If they lost life this turn, they reveal their hand, you choose a nonland card from it, and they discard that card. Otherwise, they discard a card.