VIDEOS:
The Return of Harmony
The Cutie Mark Crusaders' arguing near the petrified Discord is what results in him feeding on their anger enough to escape, kicking off the plot of the show.
Example of:
Unwitting Instigator of Doom
The Return of Harmony
Example of:
Right for the Wrong Reasons
Discorded Mane Six
Example of:
Not Himself
MLP/Star Wars
Example of:
Shot-for-Shot Remake