Den Protector is a rare Creature — Human Warrior card from Murders at Karlov Manor Commander (MKC), collector number 169. Current market price: $0.36, TCGplayer market prices via Scryfall.
Creatures with power less than this creature's power can't block it. Megamorph {1}{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, return target card from your graveyard to your hand.