Thrill-Kill Assassin is a uncommon Creature — Human Assassin card from Return to Ravnica (RTR), collector number 81. Current market price: $0.13 (foil $0.51), TCGplayer market prices via Scryfall.
Deathtouch Unleash (You may have this creature enter with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)