Is Dauntless Unity legal in Standard, Modern, and Commander?

Dauntless Unity is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Pauper, Historic.

Dauntless Unity

Q: What type of card is Dauntless Unity?

Dauntless Unity is an Instant. Its oracle text reads: "Kicker {1}{W} (You may pay an additional {1}{W} as you cast this spell.) Creatures you control get +1/+1 until end of turn. If this spell was kicked, those creatures get +2/+1 until end of turn instead."