Halfnir, Steed of the Gods

Bestow {w}{w}{w}{w} (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 to a creature.)
Flying, Trample, Lifelink
Enchanted creature gets +3/+3 and has Flying, Trample, Lifelink