A piece for bobhershey on DeviantArt. In his words…
"There's a number of Flash Sentry fans who would have liked to have seen him "pony up". I even had an idea for an animated special where he ends up with a helmet similar to the one Bulk Biceps is wearing at his costume party in the Equestria Girls Choose-Your-Ending short "Costume Conundrum". Only the helmet Flash ends up with has been infused with Equestrian magic (like Juniper Montage's mirror or Vignette Valencia's smartphone).
And at the same time former Crystal Prep principal Abacus Cinch somehow comes into possession of Equestrian magic and decides to exact vengeance on Celestia and Luna for the events at the friendship games. When she arrives at CHS and attacks, she puts one or more of the Hu-mane 7 out of commission. With them not able to harness their geode magic, Flash puts on the helmet, grabs a trash can lid and tries to protect Celestia and Luna. As he struggles to defend them the magic activates, causing him to "pony up" into what looks like a cross between an Equestria royal guard and Iron Man…close enough that the brony fandom would have given him the name Iron Sentry!"
Befittingly, I had Iron Man's and Captain America's MvC3 themes on repeat as I worked on this. Of course, this piece called for a superhero landing!