This was actually a very compelling little prologue. I've always been interested in the backstory of Equestria, and anything else that builds the world in which the canon exists.
The invention of place names was well done, Shetland Ridge, Shireton, Shadonia, they reminded me of names I might find in a Tolkien book. I give much credit to ye author for having the vision to imagine a whole separate Reich for her story to arise from. I also think that her imagined kingdom being ruled by a king and queen pair of Alicorns is a big plus. The equestrian world, canon wise, is both matriarchal, and about 2/3 female in population. Not that I want to see the roles reversed, it's just refreshing to see the males of this world portrayed as something other than evil tyrants, incompetent boobs, or meek and mild peasants.
The concept here of Discord as more than just a classical version of the trickster Loki, but as an actually malevolent conqueror is very cool. As a being possessing incredible powers, it's really a far more realistic to think of him this way. I actually like this version of him better than the show version.
Where I have to deduct points: As a fan-fic, by definition it isn't 100% original. But since the author's story involves as much original material as canon, and the story itself is compelling, I give it 4 out of five stars.
I appreciate that the prologue here probably isn't meant to be very long, but I do feel like this could be doubled in size, perhaps tripled, easily. And it also strikes me as a first draft work, I could be wrong, but this reads like the raw draft of a first effort. I think a story like this should have stuck to the board and been worked over a bit more.
I'm unsure how much impact a fan-fic can have. But I did find this story to have a very interesting premise, and I would be interested in following the story. If it's not already on FiMFiction, I would recommend putting it there, the community is much more receptive and your work will have a better life there.