According to the Exclusives section, Fan Expo in Toronto will be dropping this cover for all you collectors out there. As the submitter Captain Aileron points out:
The cover, drawn by Katie Cook and featured on issue #22, depicts the mane six and Spike at Ponyville ComiCon, posing in their new cosplays.
Fan Expo takes place on August 28-31st. We also have Tabitha St. Germaine and Andrea Libman in attendance, so it might be a good one to consider. If you want to sign up for it, head on over to this page!