Eris has found a way to escape a second stone imprisonment thanks to Tirek taking Discord's Chaos Magic, opening a tiny gap between the worlds.
Now in Twilight's Equestria, she will take her revenge on the opposite gendered counterparts of her enemies within her own world, Celestia and Luna are turned to stone and she has scattered Twilight's friends and Discord, blocking the latter's full powers, leaving Twilight on her own.
Eris confronts Twilight in her own castle and shatters her very being and causes the castle to come down around her, thinking this will end Twilight and ensuring her rule.
However, she did not count on one unicorn. Trixie has returned to Ponyville, with the intent to take the Alicorn Amulet back from Zecora, but not for revenge. She wants a child and knows a spell can give it to her, but she only wants one pony to give her her child: Twilight.
Trixie is in the castle when in crumbles and manages to save Twilight from being killed, but the way it happens she never could have expected. Now, Trixie must travel with her new child to the Crystal Empire, the one place where Eris' magic has no power, regroup with the rest of Mane 6 and Discord and figure out how to defeat Eris.
Warning: Regular nudity, large busts, lactation, breastfeeding and implications of rape (though that last one for only at the beginning of the story) are ahead. If any of these put you off, turn back now. Otherwise, enjoy.
Note: Season 5 has not and technically will not happened.
Despite what you may think, the ponies in Dusk's world were querdapeds, while the world Eris goes to is Anthro, much to her amusment.
Also, there will technically be no actual clop in this fic, though everyone will pretty much be naked unless said otherwise.