One of the more complex posters simply because of that Nightmare Moon mane.
Tons of After Effects, tons of SFM.
One where Luna becomes bitter, not only against Celestia, but against every equestrian. She firmly believed that she's been set up by them.
She had learned why she has glimpses of memory that makes no sense at all: When she was still a filly, she was different. She had slits eyes and sharp teeths, she was the future co-empress of an Empire: The Umbralian Empire and had a different name: Selenia Night-mare. Unfortunately, Starswirl kidnapped her in an attempt to bring balance to Equestrian Magic after Luna's death. And to make sure that this filly doesn't go back to her world, sealed her memory so that only Umbralian magic may break it.
Unfortunately, her first encounter with Sombra was something Starswirl never accounted for: Sombra was meddling with a form of magic that was different from Equestrian, dark, evil, sinister... Umbralian Magic.
When he tried to corrupt Selenia to make her a dark agent, it backfired: It broke Starswirl's seal on Selenia's memory and this flow of information caused her to turn into a twisted version of herself: Nightmare Moon.
She also created the batponies for one specific reason: Once she gets victorious over Celestia, she planned to allow the batponies to spread the dark news on all of Equestria that now, all the ponies has to bow to her and her "monsters".
She went on berating Sombra, telling him how miserable, pathetic he is before attempting to kill him with his own weapon. This of course failed and Selenia regained control over her emotions, but the doubt made her wondering if her place is really with Celestia.
We all know what comes next, but she finaly learned the truth from Starswirl's diary about how he had to kidnap a filly to fill in Luna's vacant spot, how Equestria would be doomed if she learn the truth.
And the truth she learned, she even engaged herself in helping the Umbralian by opening a portal to Equestria: She let hell break loose.