This is how Umarak comes for the Alicorn Magic goes in The Magic Hunt.
[Umarak arrives at Canterlot Castle]
[The princesses look up]
[Umarak tears the doors off their hitches and approaches the princesses]
[Umarak picks Celestia up and tries to drain her magic, but nothing happens]
[Umarak looks puzzled]
Umarak the Hunter: What have you done?
[Umarak then tries Luna but gets the same result]
[Umarak tries Cadance, same result]
[Umarak tries Twilight but still nothing happens]
[Umarak growls in frustration]
Umarak the Hunter: Where is your magic?!