Is Root-Kin Ally legal in Standard, Modern, and Commander?

Root-Kin Ally is legal in: Modern, Legacy, Vintage, Commander.

Root-Kin Ally

Q: What type of card is Root-Kin Ally?

Root-Kin Ally is a Creature — Elemental Warrior. Its oracle text reads: "Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.) Tap two untapped creatures you control: This creature gets +2/+2 until end of turn."