Silumgar Assassin is a rare Creature — Human Assassin card from Commander 2019 (C19), collector number 128. Current market price: $0.36, TCGplayer market prices via Scryfall.
Creatures with power greater than this creature's power can't block it. Megamorph {2}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.) When this creature is turned face up, destroy target creature with power 3 or less an opponent controls.