This is how Skull Grinder's defeat goes in The Skull Invasion.
[Skull Grinder approaches Twilight]
Twilight Sparkle: You don't have much time.
Skull Grinder: [to Twilight] I will have plenty of time, once you are destroyed.
[Then there's a loud noise]
[Skull Grinder approaches the weakened Twilight]
Skull Grinder: Now I shall erase you from existence.
[Skull Grinder raises his axe and prepares to execute her when a blast comes from behind]