This is how Umarak interrupts the wedding rehearsal goes in My Little Pony Bionicle: A Canterlot Wedding.
[Starlight hears a noise and notices a unicorn guard go round into a room and follows. She peaks through the door and watches as the guard turns into Umarak. Starlight gasps]
Princess Celestia: Perfect, girls. No need to rush. Then of course, Cadance will enter.
[They stand to attention]
Princess Celestia: I'll say a few words, and then we'll begin with the vows. Shining Armor, you'll get the ring from your best mare.
Spike: [deep voice] Do you? [high voice] I do!
Shining Armor: Hey... has anypony seen Twilight?
[Twilight walks in]
Twilight Sparkle: Sorry I'm late.
Starlight Glimmer: That's Umarak in disguise! He's been trying to sabotage the wedding!
[Umarak, knowing his cover's been blown, changes into his true form]
Umarak the Hunter: Right you are, student of Princess Twilight Sparkle.
Starlight Glimmer: And I was right all along.
Umarak the Hunter: Ah, yes, the wedding of Twilight's brother, Shining Armor, and her former foalsitter, Princess Cadance. I was quite upset about not receiving an invitation.
Shining Armor: That's because you're evil!
Umarak the Hunter: Evil?
Starlight Glimmer: Well duh, you always have been.
Umarak the Hunter: I know I've always been evil, big mouth.
Shining Armor: What drove you to come up with this plan?
Umarak the Hunter: You.
Shining Armor: Me?
Umarak the Hunter: Now to make sure you don't interfere with my other plans.
Shining Armor: Plans? What plans?
Umarak the Hunter: The plans I have for your sister.
[Shining Armor gasps]
Shining Armor: Don't you dare do anything to my sister, you monster!