After Pinkie Pie thwarts her efforts to create an army of humans for her invasion, Sunset Shimmer plots her next move while she serves time in an Equestrian prison. (A Petriculture Story.)
Pinkie Pie heads to another world to retrieve the stolen Element of Magic, with Penumbra in tow. ("Equestria Girls" as it occurs in the Petriculture AU.)
Celestia decides to attempt to reform Discord, so she taps a pony with a similar background for the job. ("Keep Calm and Flutter On" as it occurs in the Petriculture AU.)