After seeing what happened when she accidently changed her friends destinies, Twilight is curious about about the 'what if'. Like, for example, what if Luna had ponies a thousand years ago who noticed her.
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.