A Nightmare Moon mini-story

(Listen to this for a soundtrack.)

At the burnt ruins of Canterlot, the wicked mare of darkness says nothing, her mouth foaming with rage, as she is surrounded by a massive army led by the aged but immensely powerful sorceress Twilight Sparkle. Yet a voice speaks directly to her rival's mind: "My dearest friend... forgive me... even your love couldn't quell my dark half. I could not suppress her any longer... I have taken my beloved sister's life... there is no hope for me. And as long as I live, there is no hope for this world. End this madness, I beg of thee... kill me."