Moon leaned against the open door, causing it to creak under her added weight. Being inside of this room made her feel...disgusting, like something was slathering her soul in toxic substances. Anyone entering the newly-opened chamber felt the same, like they were being dragged down into a morass of remorse and fury. Of decay and longevity.
The stale air that had been stuck within was finally free to mingle with the outside and refresh itself among the plant life lurking beyond the stone. Moon peered at the contents of the room through lidded, tired eyes and felt discomfort.
The room was far from being small. It was large enough to be considered a living room or a workshop of some sort. There were several old, wooden desks that had collapsed from age. Some still hung on as tightly as possible despite their age, but it was obvious from a glance that just a slight gust of wind would make them collapse into mulch and take everything with them. Books and parchments were strewn about like someone was digging frantically through the contents, and many of them there were. Moon counted at least twenty bookshelves with six levels. The books and parchments were shoved aggressively atop each other and several were just inches away from falling down. Candles that had long since burned out had their solidified wax pooled on the floors or partially dripping off the still-solid tables. Ink wells had been shattered against the walls and floor while hundreds more lay strewn about in piles where dried ink had gathered. Several had tipped over the tables or just sat in place with feathers still resting in them.
The guide and Sunny decided to explore silently whilst watching their steps, as everything felt...wrong in this place. Sunny carefully wiped away some debris that had fallen from the low ceiling and looked at the parchments, books, and free pieces of cloth that had been used to write on.
"I don't understand. What is this place?" He grabbed a parchment in his magic and unfurled it as carefully as he could manage. "Nothing written here makes any sense. It's just random words and letters..." he frowned. "This looks like a lot of different versions of ponyish crammed together angrily."
"You say that, but the amount of magic coming off of them is insane," the guide said. "My wings are fluttering from the power."
Moon forced herself off of the door and wandered in, taking in everything around her. "Hmmm..." she growled.
"Something wrong, Princess?" the young unicorn asked.
"There's something hiding here," she said whilst looking around.
The guide followed her gaze and dropped a book that disintegrated when it touched the ground, much to Sunny's horror. "Oops," he muttered. "I'm not sure how anything could be hiding in here. It's still in pretty good shape after your fight, and nothing could have gone through that seal."
"I agree," Moon said. "The seal spreads throughout this whole chamber, but there's more. Layer on top of layer of different spells, like some cursing, muttering to itself and trying to decipher its own words without it making sense."
"A riddle?" Sunny asked.
"No no," Moon disagreed. "Like they're asking themselves a multitude of questions and getting answers that are both wrong and right."
"That's what I said: A riddle."
Moon cast a despondent glare at the stallion who smiled and turned back around to tend to the discovery.
"I can't break it or do anything about it," the alicorn grunted. "But I can at least reveal it."
Nightmare Moon focused her magic through her hooves, causing them to glow white. With a single stomp of her fore hooves her magic pulsed across the surface of the room before terminating directly above her on the ceiling. After several seconds, symbols almost identical to the ones on the door appeared all over the room, all of them a vibrant red.
"What the..."
"My sister's magic reeks in here," Moon grumbled. "Was another fragment of hers in this room?" she wondered. "Or is it just leftover magic?"
"W-well, considering it's her castle, and this is where the Solar Tyrant supposedly was defeated, one can assume this is all hers?" Sunny supposed.
"I'll have to report this to the queen as soon as possible," the guide said.
Moon grimaced. She wanted to keep all of this for her own studying, but the changelings inhabited this place, and there was no way to keep it a secret even if she killed him. The alicorn would have to accept that it was something the changelings would be able to look deeper into, and that worried her.
"This...looks like protective and summoning patterns," Sunny noted. "I saw this during our history lessons. I don't recognize the entirety of the patterns nor the symbols, but the general shape of this one looks like what I just mentioned." He sat and tapped his chin pensively. "But what were they for?"
Moon sighed internally. Leave it to Sunny to blurt out what she didn't want spoken, but she would be delaying the inevitable, so best to remove the poultice quickly.
"How are you sure that they're for that if you recognize nearly nothing?" she asked him.
He pointed to sharp corners shared between the two spells painted on the wall. "Summoning circles are sharp, while protection spells tend to be rounder."
Moon nodded in agreement. "There are circles with sharp corners but they're harder to make, and thus stronger," she muttered to herself.
"Then what kind of spell would this be?" the guide asked them.
Painted on the floor and broken by a disintegrated pile of furniture was a spell comprised of interweaving loops and words strung between each inner-most bend like rope holding them together. Sunny bounced in place, trying to dig through his knowledge of what the spell could be but started grunting in frustration.
"I have no idea! We would need to find an expert on magic!"
"I am an expert," Moon said. "And I can assure you that there are no spells like this, at least not in Equestrian magic."
"Then what?" the changeling asked. "These are fake spells?"
Moon shook her head. "They're too potent for that..." She frowned. "And they feel vaguely like the magic the false alicorn was using," she thought to herself.
He knew how to reach the castle. He had magic that could reach into a creature's mind and take it over. Moon could not trace his magic at all. She furrowed her brows, deep in thought.
"What have you figured out?" Sunny asked.
"The spells were last tended to at least six thousand years ago," Moon noted. "Meaning that there was more than enough time to study what was within."
"And you said that the spells that came after were just pale imitations, right?" Sunny asked.
Moon nodded. "The thestrals never mentioned when my sister was cast down, only that she was a long time ago."
The pair was distracted by the changeling trying to scrape away the glowing runes and bearing his teeth in frustration when he failed. "So they came across this after killing the 'Solar Tyrant' or whatever that is."
Moon snickered. "I thought the changelings would know about the stories the thestrals mention."
She was met with a hurt ego. "Not all changelings are infiltrators, and not all of us go to the same places. I wasn't assigned to the thestrals so I don't know anything about them," he explained. The guide huffed at Moon.
Regardless, there wasn't much that could be deciphered on the runes, only speculated.
"The ones responsible for destroying Equestria's past likely tried learning this magic, but without my sister they couldn't learn what they wanted," the alicorn said.
"So they just tried copying what they saw drawn all over the place?" Sunny realized. "Huh. I wouldn't try that at all. That's stupid!"
"Put yourself in the place of these foals with self-esteem issues: They take down an alicorn at the height of her rage-induced power and go to loot all her magic artifacts -artifacts which I still need to find- and discover this chamber. Why wouldn't they try to copy it and become powerful like alicorns?"
Her pupils shrunk in horrified realization. The broken pony was a false alicorn and, in his delirium mentioned being chosen as the 'hero'. She started to pace about the room, looking at all the interwoven and likely incomplete spells. He didn't mention how he became an alicorn. Moon almost felt stress encompass her but deflated quickly. They had no reason in making more alicorns outside of a pretty, living statue to bring the others towards and to worship for guidance. The alicorn took another glance at the spells and followed them to the ceiling. Somewhere in here was a way to make an alicorn, but the result meant that it was either an incomplete spell or the idiots only managed to decipher a portion of it.
"I can see you wracking your brain, princess," the guide said. "Did you decipher something?"
Moon looked around once again and started to notice patterns the harder she looked. It was obvious that there were thousands of incomplete spells scrawled in different sizes and patterns. She took one of the books and slowly turned the pages as carefully as she could before it crumbled. Every page was scrawled on with the red symbols and ink. She set it down then grabbed another. Several notes in a language she did not understand, and then blank pages, but the next book was filled with red symbols.
"The books are filled with these on a much smaller degree, and there are several journals as well, some incomplete," she noted.
She sat on her haunch and covered her muzzle with a foreleg while she turned the gears in her mind. Once more she had to look around and found herself growing annoyed at the time this was taking and the repetition she needed to do to solve the mystery. Her leg and jaw dropped when she finally saw it: There were thousands of tinier looking runes that had been angrily rubbed out or drawn over with several lines to 'erase' them. More of them seemed to bend and twist then stop immediately. Others were not even filled out yet, remaining as hollow traces or simple rings.
"She was experimenting," Moon realized. "She was trying to make some kind of new magic."
"But the chamber was sealed with increasingly worse copies of whatever could be understood and then buried entirely," Sunny added. He scratched his head, ruffling his mane. "I don't get it."
"Much to my annoyance, I don't either. Something must have happened with the magic they were using that made them want to seal it away," Moon said. She groaned loudly. "With them having destroyed Equestria's history, there's nothing else we can pull from this except for mere speculation, and I hate speculating on important matters."
"I can't find anything else of importance," the changeling said. "Nothing aside from what you mentioned already." He wiped the dust off of his chitin as he walked towards the two ponies. "Couldn't find any hidden secret passages or anything of the like, either," he added.
"Then there is not much else we can do here," Moon lamented. "I still have a chef to recruit for my castle's kitchen."
"Nothing else?" the changeling asked.
"No. We are at an impasse and must convene on the matter. I will have you inform your queen if I find anything." She stepped forward and jabbed the bug in the chest with her hoof, baring her fangs and glowing, white eyes. "And I would like the same done for me," she said through clenched teeth.
"Of course! Of course," the changeling nodded frantically.
"Good."
Moon kept quiet on the return trip and suggested Sunny do the same. Beyond a few greetings by the bugs, Sunny remained mostly silent. Back in the dungeons, Moon sealed the door behind them and exhaled loudly through her nostrils now that they were free of prying ears.
"I'm starting to wonder if they didn't seal it away because the magic they were using started to decay their false alicorn," Moon said.
"What?" Sunny said.
"He...fell apart before my eyes. He was incomplete, broken, in more ways than one, and he was filled with so much magic that it accelerated the process." She looked Sunny in the eyes. "What if that started happening in front of every pony and they partially sealed him away in the panic?"
"I mean...I guess that makes sense?"
Moon became despondent. "They resealed the room my sister was experimenting in with terrible versions of those spells, so they must have tried using it in public, and everything started to fail at the same time..." She scoffed. "Instability is fun with magic," she mused.