After discovering rifts in space-time continuum, humans have gained a technology, that allowed them to travel between different dimensions in a matter of second.

The first dimension they discovered was a peaceful world of sapient ponies, named Equestria.

But ponies didn't like what they saw. They saw a world of horrible, incorrigible abominations. Their very existence was an insult to all good and true.

From here on out, not a single pony will ever find peace again, until the last of these mosters will bite the dust.