Nithecore, The Nightmare

Bestow {6}{b}{b} ( If you cast this card for its bestow cost, its an aura spell with enchant creature. It becomes a creature again if its not attached to a creature)
Flying, Shroud
Enchanted creature gets +4/+7 Flying and Shroud
Whenever Nithecore or enchanted creature attacks, it deals damage equal to Nithecore or enchanted creatures power to target opponent.