This is how Von Nebula travels back in time goes in The Time Heroes.
[Von Nebula enters the spell archives]
Von Nebula: There must be a time-travel spell here somewhere.
[He finds it]
Von Nebula: Perfect.
[He brings it to the Cutie Mark]
Von Nebula: Time to help Twilight make her victory against Nightmare Moon alone.
[He uses the spell and goes back in time]
[Starlight and her friends arrive]
Starlight Glimmer: Oh, great, what's he doing here?
Trixie Lulamoon: Up to no good, I reckon.
Thorax: You got that right.
[Von Nebula enters the portal]
Von Nebula: Now to make sure those six ponies never ever meet each other.
[Starlight and her friends run towards him]
Starlight Glimmer: Hey!
Trixie Lulamoon: What are you doing?
Thorax: Are you crazy?
[Von Nebula ignores them]