Is Increasing Confusion legal in Standard, Modern, and Commander?

Increasing Confusion is legal in: Modern, Legacy, Vintage, Commander.

Increasing Confusion

Q: What type of card is Increasing Confusion?

Increasing Confusion is a Sorcery. Its oracle text reads: "Target player mills X cards. If this spell was cast from a graveyard, that player mills twice that many cards instead. Flashback {X}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)"