"Yes," Luna said, her expression concerned. "Therein lies the dangers of war magic. Magic is power, Twilight Sparkle, a fact you of all ponies should be aware of. And power corrupts all of us completely. Noble hearts have tried to control that potential for destruction, and I have watched them crumble, falling prey to the power they possess. Gods themselves have succumbed. Do not fear that feeling. Just do not forget it."