For a few months now, every Tuesday, a strange occurrence would bring a visitor to Equestria. Sometimes it was more than one. Some were friendly, and would come to cherish their time in the land of Harmony. Some were not so pleasant, driven by lust, greed, or wrath. They do not get to stay for long.

But the visitors of today were different. They did not come alone. Now it's up to Princess Twilight Sparkle and company to figure out not only what came through with their visitors, but how to stop it, before it stops them.

Just my take on many HiE fics and a spot of good humor towards the trope. Spoilers likely in the comments, so proceed at your own risk.