Is Rith, the Awakener legal in Standard, Modern, and Commander?

Rith, the Awakener is legal in: Legacy, Vintage, Commander.

What type of card is Rith, the Awakener?

Rith, the Awakener is a Legendary Creature — Dragon. Its oracle text reads: "Flying Whenever Rith deals combat damage to a player, you may pay {2}{G}. If you do, choose a color, then create a 1/1 green Saproling creature token for each permanent of that color."

Rith, the Awakener

Legendary Creature — Dragon

Flying

Whenever Rith deals combat damage to a player, you may pay . If you do, choose a color, then create a 1/1 green Saproling creature token for each permanent of that color.