Laughter

Pinkamena, a troubled pony since childhood and formerly the element of Laughter, has been running from the police for years as a threat to Equestria and a fugitive from the law.

So when the familiar hide and seek game ensues, Pinkamena is fully prepared with a getaway- the royal sisters' ruins, where she finds a mysterious glowing mirror... which also happens to be a portal to the fabled Human World! But in order to leave, she must unlock her past and peer past the haunting secrets that were lost (or hidden) in time.