Oh, I just had a hilarious thought. Imagine if Twilight tried a hypnosis spell to test out on her friends.... but after she does so, despite the clear differences, they think she failed and won't let her try again, leaving them quite different. Like imagine if it had turned Rainbow Dash into a peppy frou-frou girl. XD And various other changes to the others, Twilight trying and failing to get them to come back to try again. XD