Discord brings three extremely dangerous humans to Equestria. They are told to spread chaos among the ponies world. They're able to resist his corruption, but that doesn't mean Discord can't bring more bad guys.
Now forming an alliance with Princess Celestia and her subjects, the humans can only hope to return to their own realms one day.
But there are much greater things at work. They will all find out soon enough.
Gears of War - Epic games.
Skyrim - Bethesda softworks.
Team Fortress 2 - Valve.
My Little Pony Friendship is Magic - Hasbro / Lauren Faust.