AU to Equestria Girls 2. After receiving Sunset Shimmer's message, Twilight attempts to return to Canterlot High through the portal. Instead, she ends up in a world dominated by titans, where the human race is nearly extinct.
Twilight one day stumbles across a a strange book entitled "Death Note". By simply knowing one's face and writing their name in the note, that pony will die. Twilight decides to use this power to create a new Equestria with no crime or violence.