Is Den Protector legal in Standard, Modern, and Commander?

Den Protector is legal in: Modern, Pioneer, Legacy, Vintage, Commander.

What type of card is Den Protector?

Den Protector is a Creature — Human Warrior. Its oracle text reads: "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."