Equestria have long years harmony and peace thanks princess Twilight Sparkle and her friends, but peace is distrupt by appearance new villians. And these villians are much powerfull and more dangerous than previous past villians ( last time was real Grogar defeated by Mane six ) and even worse for heroes, the bad villians easily counter magic of friendship/harmony. Twilight is disbelief that harmony fail and this battle will be very hard.