Ponyville, now a literal Ponymetropolis, is a hub of trade and the center of political discussions with peoples near and far. This all gets thrown into disarray when giant blue creatures with ramshackle weaponry and giant war machines come barreling down from the stars and start destroying and scavenging everything they can. Why? Because they're bored, of course.
Barricades and spells do little to hold them as the blue creatures build things at incredible speed and have war machines up and about to destroy everything they can in mere hours. Then something else comes from the stars, something that even these creatures cannot face without severe losses, and both hate each other tremendously.
Disclaimer: This is a story to promote my space magitech novel(s) Lux Locus (And also Unholy Divination). This is still written as a proper story, otherwise it would be insulting to you all, so you will get details to understand what is going on rather than needing to read the entire book to understand anything happening here (I won't give all the details, though. Just the right amount :P).