Stratus Dancer is a rare Creature — Djinn Monk card from Commander 2019 (C19), collector number 96. Current market price: $0.38, TCGplayer market prices via Scryfall.
Flying Megamorph {1}{U} (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, counter target instant or sorcery spell.