With a WHOOM, the TARDIS arrives at The Castle of The Two Sisters. They step out and look towards
the center dais, where the Elements of Harmony have waited for a thousand years.
Or rather, where they should be waiting. Instead, there are six empty slots, and an old piece of parchment.
By the time you read this note, I, and the Elements of Harmony, should be long gone.
I came to this world because I heard of a legend of six artifacts that, when wielded together, gave their user incredible power. The legends were true, but I could not use them, for their magic refused to submit to my will.
To prevent anyone from using them against me, I am taking the Elements of Harmony. I will dispose of them, and when I find an answer to the latent magic of this planet, I will return to enact my revenge.
Twilight stares. "No. This can't be real. It's impossible. The Elements were here when our past selves got here, a few hours from now. This must be what the Map sent us to fix! Without the Elements of Harmony, the us from this time won't be able to defeat Nightmare Moon, and the timeline will fall apart."
"What do we do?"
"Unless anypony here knows of another set of six powerful magical artifacts, we've got to find a way to get them back."