Root-Kin Ally is a uncommon Creature — Elemental Warrior card from Modern Masters 2015 (MM2), collector number 158. Current market price: $0.04 (foil $0.30), TCGplayer market prices via Scryfall.
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.