Thalakos Dreamsower is a uncommon Creature — Thalakos Wizard card from Tempest (TMP), collector number 92. Current market price: $0.25, TCGplayer market prices via Scryfall.
Shadow (This creature can block or be blocked by only creatures with shadow.) You may choose not to untap this creature during your untap step. Whenever this creature deals damage to an opponent, tap target creature. That creature doesn't untap during its controller's untap step for as long as this creature remains tapped.