When twilight hits a wrong key on the Doctor's new "Calculator" and accidentally divides by zero, all hell breaks loose.
The old Discord meets the new Discord,
Nightmare moon meets princess Luna,
Unicorn Twilight meets Alicorn Twilight,
Ect.

This is not a parody of 'Dividing' by Zero by The Offspring, but it would help to have that song playing during the fight in chapter 3.