Is Boreal Outrider legal in Standard, Modern, and Commander?

Boreal Outrider is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

What type of card is Boreal Outrider?

Boreal Outrider is a Snow Creature — Elf Warrior. Its oracle text reads: "Whenever you cast a creature spell, if {S} of any of that spell's colors was spent to cast it, that creature enters with an additional +1/+1 counter on it. ({S} is mana from a snow source.) Power/Toughness: 3/2"

Boreal Outrider

Snow Creature — Elf Warrior

Whenever you cast a creature spell, if of any of that spell's colors was spent to cast it, that creature enters with an additional +1/+1 counter on it. ( is mana from a snow source.)