Nyxborn Triton is a common Enchantment Creature — Merfolk card from Born of the Gods (BNG), collector number 46. Current market price: $0.15 (foil $0.13), TCGplayer market prices via Scryfall.
Bestow {4}{U} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached.) Enchanted creature gets +2/+3.