Is Bloodstoke Howler legal in Standard, Modern, and Commander?

Bloodstoke Howler is legal in: Legacy, Vintage, Commander, Pauper.

What type of card is Bloodstoke Howler?

Bloodstoke Howler is a Creature — Beast. Its oracle text reads: "Morph {6}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.) When this creature is turned face up, Beast creatures you control get +3/+0 until end of turn. Power/Toughness: 3/4"