Is Prohibit legal in Standard, Modern, and Commander?

Prohibit is legal in: Modern, Legacy, Vintage, Commander, Pauper.

Prohibit

Q: What type of card is Prohibit?

Prohibit is an Instant. Its oracle text reads: "Kicker {2} (You may pay an additional {2} as you cast this spell.) Counter target spell if its mana value is 2 or less. If this spell was kicked, counter that spell if its mana value is 4 or less instead."