My Little Pony: Friendship Is Magic Season 3 Episode 13
Twilight Sparkle accidentally casts a spell that switches the Cutie Marks and destinies of all her friends, and the only way she can reverse the spell is by writing her own magic. Little does she know that by achieving this great accomplishment, she will fulfill her destiny and emerge a princess.
Episode Title: Magical Mystery Cure
Air Date: 2013-02-16