Is Strength of the Coalition legal in Standard, Modern, and Commander?

Strength of the Coalition is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

What type of card is Strength of the Coalition?

Strength of the Coalition is an Instant. Its oracle text reads: "Kicker {2}{W} (You may pay an additional {2}{W} as you cast this spell.) Target creature you control gets +2/+2 until end of turn. If this spell was kicked, put a +1/+1 counter on each creature you control."