Princess Celestia may be trapped in a box, but I can see her prevailing.



Celestia uses her magic to summon the slice of cake to her, but Luna then tries to prize it from her with her own magic. But Celestia being the eldest of the 2 and having stronger magic, overpowers her younger sister's magic and eats the cake.



Celestia "Hmmm, tastes like Pinkie's recipe."



Pinkie "It is, Princess!"



Celestia "And no doubt the box came from my faithful student after she moved in some time ago."



Twilight "Guilty as charged!"



Celestia "And I bet Luna was the mastermind of all this."



Luna "You got that right!"



Celestia "Joke's on you, Sis, I still got my cake."