Herdchaser Dragon is a uncommon Creature — Dragon card from Dragons of Tarkir (DTK), collector number 190. Current market price: $0.28 (foil $0.89), TCGplayer market prices via Scryfall.
Flying, trample Megamorph {5}{G}{G} (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, put a +1/+1 counter on each other Dragon creature you control.