Anon-a-Miss succeeded.

It dissolved friendships left and right and framed Sunset Shimmer as the guilty party. The result was that everyone is now out for her blood, including the Rainbooms. She flees to Everfree Forest and ends up in a coma as a result.

Now, the tables have turned as a spirit hell-bent on revenge and justice seeks to punish everyone at CHS in the worst way possible. Of course, one simply does not invoke magic without alerting Twilight Sparkle and her new allies.