This is how Twilight becomes Nightmare Nova goes in Revenge of the Sith.
[The medic droids try to repair Twilight]
[She screams in pain]
[Then we cut with Discord as he sees his twin children]
Discord: Is it a boy or a girl?
[The capsule goes up]
[Nightmare Nova breathes]
[Nightmare Moon speaks to her]
Nightmare Moon: Lady Nova, can you hear me?
Nightmare Nova: Yes, Masteress. Where is Discord? Is he safe? Is he alright?
Nightmare Moon: It seems, in your anger, you killed him.
Nightmare Nova: I? I couldn't have. He was alive. I felt it!
[She destroys all medical tools and frees herself]
[Nightmare Moon grins as Nova screams]
Nightmare Nova: NOOOOO!!!!!!
[She wains in defeat]