Is Skittish Valesk legal in Standard, Modern, and Commander?

Skittish Valesk is legal in: Legacy, Vintage, Commander.

Skittish Valesk

Q: What type of card is Skittish Valesk?

Skittish Valesk is a Creature — Beast. Its oracle text reads: "At the beginning of your upkeep, flip a coin. If you lose the flip, turn this creature face down. Morph {5}{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.)"