Come around and see the mixture of two stories. One were ponies start meeting changelings through the lenses of six ponies now, turned changelings, and another one of queens facing the changing of history through their eyes.
Starlight and Twilight drink a potion which reveals the downward spiral one of Starlight's alternate universes took. Meanwhile, Twilight watches Starlight take a downward spiral of her own.
Everything fell apart for Rainbow Dash after the Mare Do Well incident. Bent on vengeance and driven by her raw emotions, Rainbow Dash becomes a villain that Ponyville won't soon forget.
Twilight Sparkle: a name often associated with magic, friendship, harmony, and most recently, ascendant princess of Equestria. Nopony, not even herself, could have thought that she would be a changeling.
Twilight Sparkle’s brilliant mind was gone, burned away by her own power when she nearly destroyed Canterlot twelve years ago. Now there is a monster prowling the Everfree. And it is starting to remember what true power felt like.