Princess Luna finished a magical scan of Rarity and confirms that there are definitely traces of Nightmare, the entity that turned both of them into Nightmare Moon and Nightmare Rarity in years past, still there. She casts the Aura Vision spell used to identify the kaiju and alters it so Rarity can see what she sees. Rarity is able to see her magical aura, which is largely very bright and a shade of royal purple that matches the color of the Element of Generosity. However she soon notices what Luna was talking about when she spots dark smudges, some so black they look like a void more than a color, spattered across her aura. She, understandably, is very distraught by this and nearly breaks down thinking her worst fears have been confirmed. Princess Luna stops her and pulls her into a hug. It's here Luna tells Rarity more about the nature of Nightmare, that it is not entirely an outside force that possesses ponies unwillingly and that it needs a willing host. Princess Luna casts the aura spell on herself and let's Rarity see that while she also has an extremely strong, blue aura with sparks that indicated remnants of the Elements for Honesty, Loyalty, and Laughter; she also has the dark blotches that show remnant traces of Nightmare.
Rarity begins to despair again, worrying she'll turn into Nightmare Rarity again and threaten everypony and Luna affirms to her to listen close.
"Juliet Rarity Belle, listen to my words. Any sentient being with the power of reason will have the potential for good or evil thoughts, words, and deeds. The Nightmare is an expression of the latter. Had that darkness been fully expressed and let loose in anypony, then anypony from my sister to the Bearer of Kindness could have the potential to become a Nightmare."
The point is, anypony has the capability of being consumed by negative emotions. The dark blotches on Luna's aura slightly resemble Junior's scars, which is partly the reason why seeing them gave her pause. Luna decides to tell Rarity of Nightmare's origin. A thousand years ago, Luna became jealous of Celestia overshadowing her in popularity and dreamed of surpassing her. Her dream was so powerful it became real; Nightmare Moon was her idealized body, equal in age, size, and power to Celestia. When the Elements of Harmony changed her back, Nightmare had grown enough in power to be able to exist without a body, though requiring a host to interact with the world.
Rarity remembers how she fell into temptation to become Nightmare's host. She feared becoming forgotten and replaced, so Nightmare Rarity was an unforgettable dark beauty.
Luna explains she has the ability to create things from her thoughts. She opens a secret compartment inside a wall mirror and draws out a sphere containing a formless, inky black mass. She explains it is the Tantabus, an incomplete being similar to Nightmare. She started working on it a year ago, and when it was finished, she would have used it to torture herself with nightmares to atone for her sins. She put it away when the kaiju arrived and now that she knows Junior faces similar guilts, she's realized she isn't alone and doesn't have to punish herself, so she's discontinued working on the Tantabus. Luna then encourages Rarity to stop attacking herself; she made a mistake in joining Nightmare, nothing more, nothing less. Rarity is a hero, and in the end, she was able to break Nightmare's hold on her, allowing her friends to defeat Nightmare Rarity. Luna then asks her to help put the Tantabus away. The two combine their magic and start sealing it back in the secret compartment, but Luna suddenly stops, so it's solely Rarity's magic doing the sealing. Luna says to think of it as a symbolic victory over her fears. Rarity grunts with effort but manages to seal it, causing the two to grin.
Somewhere else in the castle, Celestia, the rest of the Mane Six, Shining Armor, Cadance, Godzilla Junior, Mothra Lea, Rodan, Anguirus, Xenilla, and Destroyah gather. Celestia welcomes them and asks for a report. Twilight Sparkle reads from a scroll that Starfall, who is recovering in a hospital, told a tale of being attacked by giant beetles until he was rescued by a black and white biped. The social worker Marigold reported giving this being a raincoat and a museum guard reported getting attacked by him. Junior says that description sounds like Monster X. Fluttershy comments that if he saved Starfall, he can't be all bad, while Lea agrees that X never attacked civilians in the past, but warns that he's still dangerous. Celestia explains that X stole the Alicorn Amulet. After explaining to the kaiju what it does, Lea comments that the amulet would be useless to X because his powers are not magical. Rainbow Dash asks how he would even know to look for it, so Lea explains that many kaiju can sense energy, including magic. Xenilla adds that this is why many kaiju attack cities, because they are attracted to the electricity.
Xenilla asks how many other sources of powerful magic are out there. Celestia answers the Tree of Harmony, herself and Luna, the Crystal Heart, and the Mane Six themselves. Anguirus agrees, saying he can smell a difference between the magical energy the Mane Six have compared to ordinary ponies. Celestia grants everypony in the room the ability to see auras. The kaiju transplants' auras are of their true forms. The Mane Six's auras are much brighter than Shining Armor's, enhanced by their exposure to the Elements of Harmony. Cadance's aura is bright and crystalline, similar to the Crystal Heart, while Celestia's blazes like the sun, with traces of the Elements of Harmony's colors in it. Celestia cancels out the aura vision and explains that although she can no longer wield the Elements of Harmony, she still has trace amounts of their magic. The Mane Six may have given them back to the Tree of Harmony, but they still have a lot of their power. This was how Rainbow Dash was able to transform Anguirus in order to save the camp from the dragons. Celestia suggests figuring out how to do that at will, since they are all going to be targets.
Applejack, Fluttershy, and Rodan speak up about something they discussed on the train. They pull out a map of Equestria and say that based on what they know about the Gyaos, it doesn't make sense that they ignored Dodge Junction after attacking Appleloosa. Rodan mentions that Gyaos can't stand sunlight, so hiding in the Everfree Forest would make sense, but they ignored everything between Appleloosa and the forest. The only explanation is that they were attracted to the energy of the Tree of Harmony. Celestia admits she's not an expert on the Tree, but something as powerful as a kaiju might be able to destroy it. She suggests they take turns guarding it. Junior suggests moving the magical items and ponies out of populated areas, but Celestia warns this isn't very feasible. The Crystal Heart is crucial to keeping back the northern storms so much that it cannot leave the Crystal Empire. Celestia and Luna are needed in Canterlot, but can easily move to another location if it is attacked. But besides Rainbow Dash, the Mane Six are not as mobile.
Pinkie Pie suddenly pops out of Anguirus' tail, scaring him, wearing a pair of boxing gloves and boasting that they've handled dangers before and this will be no exception. Amused, Twilight agrees that if they and the kaiju stay in Ponyville, they should be relatively safe since that's were most of the Elements of Harmony live and there are large rural places around the town the kaiju could take any fighting. The kaiju agree to protect them, but Xenilla feels a little down because of his past crimes and says at least this should help him atone. Pinkie tilts his head up and says with his rescue of Cadance, he's on the right track. Shining Armor is still a little mad that Xenilla caused a lot of property damage and used Cadance as bait to lure in Sombra. Cadance reminds him that she and her unborn child are alive because of him. She herself may not like him much, but they should give him a chance. The couple invite Xenilla to help protect the Crystal Empire again, and he agrees.
Twilight asks how they can predict future kaiju attacks. Because of Manehattan's many lights, it would most likely be attacked next and with such a high population it could be a catastrophe. Celestia says that she had earlier safeguarded several cities with anti-Changeling wards, modified to not do anything to Mothra Lea, and can modify them to detect kaiju as well. Celestia also says that she can see visions of the future in dreams, but warns that it's not very reliable, as she had a dream about the Gyaos attack on Canterlot a very short time before it actually happened. Mothra points out Godzilla has the ability to sense danger and move to where he is needed, but he points out that's not very reliable either. Destroyah speaks up and tells them all to stop worrying, between Celestia's dreams and Junior's psychic precognition they should be well covered.
Celestia asks how many other kaiju are here. Mothra says that every extra shot of Dimension Tide brought in an enemy. Twilight reports that based on the skeletons found in Whitetail Woods, the Albino Hyper Gyaos is the only remaining Gyaos. They know of her, Monster X, and the beetles that attacked Starfall. Fluttershy interrupts and gives a request. That any hostile kaiju who is sentient be given the chance to surrender peacefully and only be killed if there is no other option. She points out Xenilla and Destroyah have redeemed themselves, and if Monster X could save a pony's life, then they all deserve a chance to change. Anguirus speaks for the kaiju and agrees.
Celestia says that is splendid and the six kaiju will soon be announced to the world to show the others they are on their side. She then announces that Cadance is pregnant. The Mane Six and Lea become excited, while Xenilla matter of factly says he already knew that. With his ability to sense anything that happens near a crystal, he could hear a second heartbeat coming from her belly. He never brought it up because he assumed the couple already knew, annoying the couple.
Queen Chrysalis steps through the portal into Zenith. She immediately feels the insane cold, but straightens up, determined not to show any weakness. She beholds the sphere that holds Bagan, so large it could fit a castle inside. The floor shifts and elevates her to it, then part of the sphere opens up, exposing a dark void within. Bagan levitates King Sombra's horn and charges it with magic, causing it to regenerate until Sombra is restored to life. As the last thing he remembers is Xenilla and Cadance's final attack that wiped him out, he thrashes around trying to defend himself until Chrysalis tells him to calm down. Bagan addresses them, and they turn around and are terrified to see the sphere fall apart and Bagan standing before them. He is so huge that they are like ants compared to him.
Sombra asks what the Hell that is. Chrysalis regains her composure and explains this being is their ally who has agreed to help them restore their master Grogar to power. Bagan asks what is needed to do this, so they explain that the portal to Tambelon is under the Crystal Empire. To open it, they require all four tomes given to Grogar's students and a portion of Harmony's magic. Sombra's tome is somewhere inside the Crystal Empire. Bagan explains he cannot teleport Sombra inside the Empire because its magic obscures his vision. Bagan comments that if they need Harmony's magic, then it's a good thing he failed to kill her. Chrysalis and Sombra become scared because Harmony was the one who defeated and sealed away Grogar. Sombra says they can recover the tomes, but they don't actually need Harmony. Any magic similar to hers, like an Alicorn's, should work. Chrysalis says with the anti-Changeling wards in place, her people's ability to infiltrate cities and abduct who they need is limited. Sombra suggests they try finding Tirek to recover his tome. Bagan tells them to work on that while he takes care of the wards.
Chrysalis and Sombra step through a portal to the Changeling hive. Sombra angrily lashes out and pins her against a wall. Having gone through this before, she is bored while he berates her for making an alliance with such a dangerous being. She wonders if she has to seduce him by transforming into Princess Amore again to get him to chill before deciding not to. After confirming Legion and her minions are not here, she says of course she doesn't trust Bagan. They'll just use him to free Grogar, then Grogar will kill Bagan.
Bagan scans several worlds for magic matching Princess Celestia's and finds something promising. He sends his minion Mizu, the Aspect of Water, into the human realm of the Sirens and Sunset Shimmer. The sea monster transforms into a vaguely human shape, a shadow man with blue lines along his body and a jewel on his forehead. With his ability to enter a reflective surface and emerge from another one, it quickly travels through town, unseen by the humans, but causing all the animals to panic.
Mizu emerges near Sunset Shimmer's rental home, where she is asleep, then approaches her car. A tiny fragment of Enjin's core is embedded into the car's underside from when Monster X and Enjin fought in the national park Sunset drove through. Mizu retrieves it, then enters Sunset's room. It sets the fragment down near the bed, then leaves. The fragment reacts to the magic within her and melts into liquid. Sunset wakes up, but it is too late as the fragment leaps onto her. She struggles, but it's over as her body is possessed by Enjin. Her eyes turn black but with the kanji for "Land". She is transported to Zenith.
Bagan welcomes his new Aspect of Land. Sunset's body changes from a human to an oddly colored pony with unnatural size and proportions. Deciding that won't do, Bagan has her change her form to look like how she normally looked as a Unicorn. Bagan orders her into a portal to Equestria, then orders Mizu to enter a different portal to a new world he discovered, setting the stage for Mizu's presence in The Bridge: A Shimmer in the Dark.
The new Enjin arrives somewhere in Manehattan. Sunset Shimmer is unconscious, but Enjin is able to access her memories and knows what to do and where to go. Her body changes into a Unicorn mare with a cold blue body and a magenta mane. She disappears into the crowd.
