Takes place during the events of “The Beginning of The End” episode.
Ever since the day that Sombra had finally taken over all of Equestria; he was very proud of himself, and happy that things are finally going his way. However, when the Mane Six showed up to stop him, he didn’t expect the results to wind up so, “childish”. Regardless, he has a responsibility now; and it’s definitely gonna be one that he won’t enjoy; not even if it were to happen again somehow.