In the alternate timeline where Sombra was not stopped, a human finds himself suddenly in Sombra's body... just after the dread tyrant has conquered Equestria.
One crazy pegasus, one roboleg, a contingent of Steel Rangers, and an adventure of infinite detours. Put all that together and what do you get? A rip-roaring mosh pit wrecking its way across the Wasteland, leaving nothing but confusion in its wake.