Animal Attendant is a uncommon Creature — Human Citizen card from Avatar: The Last Airbender Eternal (TLE), collector number 128. Current market price: $1.30 (foil $3.14), TCGplayer market prices via Scryfall.
{T}: Add one mana of any color. If that mana is spent to cast a non-Human creature spell, that creature enters with an additional +1/+1 counter on it.