The final episode of the season has been revealed over on Zap2it. You know the drill at this point I think! Head on down below the break for the summary.
Season 3 Episode 13
Magical Mystery Cure
Aired Date: February 16, 2013
Synopsis: When Twilight casts a spell that switches the Cutie Marks and destinies, the only way to reverse the spell is by writing her own magic.
As for the princess coronation event, I haven't a clue how this will relate to that!