Is Aquamorph Entity legal in Standard, Modern, and Commander?

Aquamorph Entity is legal in: Modern, Legacy, Vintage, Commander, Pauper.

Aquamorph Entity

Q: What type of card is Aquamorph Entity?

Aquamorph Entity is a Creature — Shapeshifter. Its oracle text reads: "As this creature enters or is turned face up, it becomes your choice of 5/1 or 1/5. Morph {2}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)"