Is Requiting Hex legal in Standard, Modern, and Commander?

Requiting Hex is legal in: Standard, Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Requiting Hex

Q: What type of card is Requiting Hex?

Requiting Hex is an Instant. Its oracle text reads: "As an additional cost to cast this spell, you may blight 1. (You may put a -1/-1 counter on a creature you control.) Destroy target creature with mana value 2 or less. If this spell's additional cost was paid, you gain 2 life."