It would cost them twice as much power to fight such a person, because of the dark power that person might be wielding. But they should be thankful for being unable to meet such a person in a time where their powers do not take action. They are only powerful at night when the full moon is visible in the sky. Mephiles often keeps his power locked inside his soul until a mighty encounter takes place in his kingdom. He had nothing left but the body of a man he consumed after he fought against King Harald.