This is based on a scenario i have involving villains with armies or militaries backing them (Sombra, Chrysalis and Storm King) launching invasions into the Human world with the intent of making that world their new domain and enslaving mankind to their will. Equestria eventually following them in and a war of apocalyptic proportions ensuing as the Equestria fights to thwart the plans of these villains and save an innocent species from their wrath and cruelty. But their fighting has the unintentional effect of ravaging the planet with magic from their fighting, anything from Equus that could pose a threat to human life leaking into Earth unchecked or through "wild" rifts similar to the ones seen throughout the Equestria Girls spinoff as a consequence of the portals being open for extended periods of time.

This scenario is specifically for the Crystal War Timeline. a situation where the final moons of the Crystal War see the conflict shifting into the Human world. Earth becoming the setting of the final theatre of the war.

How this would begin would be the result of Sombra's own research into building his own trans-dimensional portals upon learning of the Crystal Mirror and the Human world that lay beyond. As he would not be able to access existing portals into that world, he would build his own portals that would eliminate the flaws and negative aspects of the existing ones. As in they dont change forms, won't be stripped of magic and are big enough for entire armies to send through.

Upon learning that the Humans have no magic and in his mind, are defenseless and easier to conquer than ponies, he was emboldened to launch an invasion of the Human world with the intent of making that world his new domain and to use it's resource to strengthen his army and enslaving it's most dominant species. Robbing them of their humanity and individuality in order to massively increase the numbers of his army of Mind-controlled soldiers.

Equestria, believing the sudden withdrawal of Sombra's forces to be a sign of him losing would be horrified once spies reveal that he's actually transferring his assets and even the crystal heart into the humans world as well as hearing of his plot to conquer it. Two things could happen. Either Equestria follows them in using the portals set up by Sombra or Celestia goes through the same process of developing her own portals that also eliminate flaws that the mirror has. In both cases, they intend to thwart Sombra's plans to conquering the Human world and save an innocent species from undeserved misery and suffering.

At this point, I'm gonna be brining up Darksiders for this scenario. Particularly making the war in this scenario be similar to the (Biblical) Apocalypse from the game series down to the level of destruction this war will inflict upon the Human world.

As in it gets this bad:

Why Darksiders? Because I thought it would be cool to imagine this kind of fighting:

raging in the streets of Human cities and inflicting this level of apocalyptic destruction. Weaponized magic wreaking havoc on Human infrastructure and reducing whole cities into ruins:

On sombra's side, the devastation was intentional, on Equestria's side, it's merely collateral damage they didn't intend to inflict.

As Sombra arrived first and was in the Human world for much longer than Equestria, much of the devastation was his doing and using his dark magic, crushed any military that dare stand in his way or put up any meaningful resistance against his wrath, which is why Humanity , by the time Equestria arrives, is rendered defenseless and vulnerable. In places on Earth, the ponies would be greeted by this horrifying landscape before them:

Off in the distance in one such city, Sombra's new palace and the new dwelling of the Crystal Heart:

Regions beyond Sombra and Celestia's warring end up having to face an invasion from an entirely different enemy. Invasive species and magics from untamed places on Equus such as the Everfree forest which when introduced to this new environment would quickly thrive and threaten the already existing ecosystem or human infrastructure. Proceeding to overtake and expand uncontrollably across portions of Earth:

In other places, dragons have invaded into Earth as well. A freak event occurred in which all canine species reverted into dragons. They proceeded to turn on their masses and, well...

To compound things even more, Dragons from Equus, having been displaced by Sombra's expansion into their homeland and the ruination of said homeland by his dark magic, stumbled across some rifts and entered into the Human world. Their fighting with the wild dragons, formerly dogs, adding further destruction to these formerly human lands:

so with that sunny exposition out of the way . What kind of stories do you want to write, set in this scenario?

7828362
How many groups are you gonna get chased away from before you write this goddamn story?

the Crystal Wat Timeline

Now I'm picturing Angkor Wat, but made from Pony crystal, and it's glorious.

7828365
Probably never.

7828362
This 'could' be a good fic. {Minus the Darksiders game}

7828599

I'm just trying to keep with the dystopian feel of this timeline. Also, I'd imagine that magic that destructive as a result of an arms race between both equestria and the crystal empire.

7828625
Alright. So are you going to do it or?...