Thinking it over, neither Asta nor Lucas found a good answer right away. There were some random thoughts that floated in their head, but speaking them out loud revealed nothing.
Still, there was no point in panicking. If time truly moved slower here, it meant they could mull it over as many times as they wanted. They had enough of it to enjoy some time off. Not that either were slackers, in fact, the opposite occurred.
With time aplenty, Lucas and Asta started to focus on building their spells and Rank. Using Yaldor as a mana machine, they used his mana to circulate the energy through their core. Doing it for a few thousand times, a small rune appeared, showing the progress after a day or two.
Yaldor didn't mind, he was loyal to Asta's father and knew this would only help the family.
Part of Lucas often requested spars with Yaldor, who showed no interest or refusal. He couldn't teach Lucas any spells, for he was forbidden to do so, but simply fighting wasn't that much of an issue.
"Yaldor, do you know anything about spatial magic or runes?", Lucas asked randomly after a though fight. His own body in tatters, and with Asta sweating bullets, questions he held for a long time could finally be answered.
"I know some spatial runes, but I wasn't able to understand them. Using them carelessly would even put someone like me in extreme danger. Since I lacked the talent, the Duke placed me elsewhere."
"So the Duke has an entire team studying space related magic?", Lucas wasn't just asking questions out of the blue. He held a few connections in his mind but needed more intel to truly connect the dots.
"No, as far as I'm aware, the Duke has 13 Guardians, of which only one is Rank 2. That person is also the only one who can use spatial magic to a certain extent."
Not bothering to hide his intrigue, Lucas pursued the topic further. "Rank doesn't help with understanding it?"
Chuckling slightly, "If you're twenty or forty years old, high level math stay of the same complexity. This isn't just about learning and studying, anyone can accomplish greatness using those. This is about your talent."
Snapping his fingers, orbs of fire appeared around him. "I have a red core. While one of the most common one, my talents lie in that field. You may think these balls of fire seem static, no?"
Asta released his aura to study them. "Yes, they are formed using 27 runes split in three phrases," raising his head slightly, Asta showed his genius boldly, since even Lucas, who actually used elemental magic couldn't figure it out so quickly.
"Wrong."
"What?", Asta's cockiness instantly backfired as Lucas had a laugh.
Yaldor moved his hand slightly, the orbs of fire turned into tiny snakes that rested on his shoulder and head. The intricacies in the form were incredible. Just the amount of detail was unnecessary for a spell, yet Yaldor didn't seem to put in any effort.
"This is talent, or more accurately, your proximity to the true essence of the element. I wasn't born with this power, I worked hard to get to where I am. But plenty of other people followed the same path, yet weren't capable of what I am."
The fire snakes floated upwards and started to dance in the air before exploding into fireworks.
"The runes I used aren't simple ones, they are flexible. It's not just about replicating the sound or writing it correctly. You need to truly understand what they are about. It took me a hundred years to gain a small glimpse of the true meaning of a single spatial rune. The Space Guardian took half a decade to learn two."
Giving the span of times, both Lucas and Asta couldn't grasp their head around it. They were both certified geniuses, yet they both were too young to have studied a single topic for tens of years. Even one of the longest running projects of Lucas was only going on for a couple of years.
"Your core allows you to draw closer to the true essence at a much faster pace. Sure, anyone could study it, but before showing results, one would spend half their lifespan holed up in a study. Forgetting about the outside world and focussing purely on one's craft is exceptionally rare. So, we stick to our talent. What's yours?"
It was an open question, but alarm bells went off in his head. Perhaps due to treatment on Aurora, Lucas had grown used to hiding certain abilities. His shock was quite hidden, but Asta picked up on it.
"Don't worry, we demons care little if you use Dark magic," piercing through his defenses with a single sentence, he laid the root of the problem bare.
"So you knew?"
"Of course, after seeing you in that Darkness Pool back on the island and seeing your darkness project, it's only natural to come to that conclusion."
Asta smiled wide, happy to have figured out something that was meant to be secretive so easily. Combining past and current events to come to a sweeping conclusion was a most effective strategy, though not always as easy to accomplish.
"Yes, I have a Dark Core," Lucas spoke as if he was revealing all his cards, letting his shoulders loose and heaving a relieving sigh, even Yaldor smiled slightly.
"It's quite unique, a Dark core. Even here on Sabaoth, there's rarely one found," a light smile of respect appeared on his face, knowing he was standing near an extremely rare or even legendary core.
Hearing them talk about the history of the planet, Lucas was completely absorbed in himself.
'Look, I'll only say this once, so open those big ears of yours. Thank you for deceiving them so well, master devil.'
'Would you stop?'
'C'mon, the acting and all, it's incredible, even I believed it for a second.'
'If we revealed we are mostly a Light core, I think that Yaldor fellow wouldn't be so friendly anymore.'
'Exactly, the fucker looks kind and friendly, but any mage that's lived for so long and holding no ulterior motives is a bastard or has gone senile.'
'He might help Asta, but us, we're probably just another slave in his eyes.'
Seeing that Yaldor was finishing up his explanation, Lucas looked towards Asta with curiosity.
"As far as I'm aware, there's no core that is without an element," since Asta didn't use any kind of element, it would mean all his talent was being squandered by petty pride, not that Asta needed elements to be a powerful opponent. It just showed how much more powerful he could be if he used his own tools to the fullest.
"I can't say if that's true or not, there are plenty of strange legends out there. Either way, I have a light blue gray core," spoken with no joy or pride, it felt like recounting a sad past.
"Gray?"
Yaldor wasn't surprised since he already heard from the Duke. Lucas on the other hand didn't know what it meant.
"Gray is observed in very few people. Even less than darkness, not because it's a good trait to have, but because it's a piece of dead core. In other words, the Young Master is walking around with a constant handicap, limiting his total mana capacity."
Staring at Asta, Lucas didn't know what to think.
"Don't even give me that look, you! I'm a genius, do you think it would be fair if the world didn't stop me in some way? Besides, I can gather mana there, it's not fully dead yet."
Choosing silence over an answer, Lucas felt a strange question pop up in his mind. "Why do you use Pure Mana then? It's the most expensive mana-wise."
"You misunderstand my tools, Lucas. Pure Mana is more expensive in the beginning, but unlike you elemental mages who waste mana just by keeping their spells active, I don't have to anything. They are an investment in the battle, when you summon a Blue Fire Sword, you quickly throw it away due to the energy cost. My sword can be thrown and retrieved later without any additional cost."
"Hah, so the most expensive magic was the most cost-effective?"
"Yes, it's just very poorly understood among the many elemental mages. I told you long ago that my techniques are superior. I still wonder why you haven't joined me on my path."
Yaldor shook his head in disappointment. "You should really try to use other forms of magic, Young Master. Even just your demonic powers would be a massive boost to your current combat ability."
"I won't hear it, Yaldor. I'll show you how powerful my techniques are."
Taking a stand beside Asta, Lucas prepared his magic. Yaldor snapped his fingers to summon a couple of large fire snakes, each intimidating on their own. What ensued next was a spar that tested Asta's and Lucas' tactics.
Since time moved slower, they sparred daily to improve their spells. Still, they weren't able to land a single hit on Yaldor. Seeing no direct change, Lucas decided it was time for his other self to take over.
Switching, Lucas became a lot more ruthless during the fights, making the battlefield a lot more chaotic. Asta joined him at every chance he got. Not only did their tactics improve, Lucas and Asta had perfect synergy, making them an actual fair opponent for Yaldor. Not that they every got a chance to hurt him, nor was it their main goal.
Just by fighting daily, they got used to their new spells and combination attacks. Lucas even requested Yaldor to use his aura to pressure him. Under the constraints, Lucas tried to temper his own aura, Asta followed his tactic, gladly enduring the pain and suffering that came with it.
A year had passed in the blink of an eye. As they trained and worked on their own projects, Lucas eventually finished his prototype to destroy Protares' county. After achieving it, Lucas realized that without the help of this temple, he would've barely made it in time back to Sabaoth. Not that he only had a single plan to rely on, of course.
Taking Asta to the obelisk to think over the riddle, Lucas wanted to separate them from Yaldor so he could go over it without him overhearing them.
"It starts pretty harmless, but will spread like wildfire, after having infected enough people, it should be lethal to most people," presenting his product with a big smile, all Lucas had was a small vial of pure mana with some clear liquid inside.
"Can't we just remove the infection by using magic? You wouldn't see me using Dark mana, but I believe many of the fools outside use it without thinking," Asta wasn't exactly excited to know they now held a weapon capable of killing too many innocent people.
If Yaldor was here, he would be able to shed light upon the fact that some Rank 2's and all Rank 3's and up would be able to deal with it, but that wasn't their target in the first place.
"Yes, you can probably cure it with magic, it was created by magic in the first place."
"Tch, Dark Magic truly is a blight upon the land, isn't it?"
"Hah, most of the runes I had to use were associated with Light, you know?"
"What?"
"This is an artificially made virus, essentially copying a lifeform. There's no black magic involved here."
"Why would they even create such a spell in the first place?"
"In Aurora, I don't think it would matter that much. There are so many powerful mages that solving an epidemic would take a few days at best. According to the tome I got the instructions from, it was mostly used to remove people from land they wanted to occupy or remove an overpopulation of something. Here, I don't think the demons have developed their light magic enough to figure out how to counter it."
"Have you?", while creating such a thing took a lot of effort, if they weren't able to cure it, they would be in even bigger trouble.
"Well, I know how I made it, and I have the instructions on creating a cure, it'll just take some time."
Asta sighed for a moment, "Well, that's the one thing we have here, let's make use of it."
Unlike back on Aurora, Lucas didn't want to use it to make the people suffer if there were other solutions, but now, Asta himself was willing to use it without hesitation. Surprised for a moment, Lucas scolded himself for not being as decisive as his friend.
They went back to work on their progress on the path, their spells, their tactics against Yaldor. Keeping it interesting, Lucas tried to experiment with his personalities, switching in the middle of a fight to completely throw Yaldor off.
After plenty of experimentation, Lucas and Asta were able to land a few hits, showing their improvements. Being so blatant with his switching, even Yaldor started to notice the big changes. From the posture, the speech, just the whole personality, it was like talking to a different person. Finding it hard to hide his curiosity, after their spar, Yaldor asked Lucas about his sudden changes in fighting style, but Asta stopped him.
"You don't have to get into his head to know why he fights the way he does. He's my friend, the entirety of him."
"Glad to hear that, Rophy."
"Don't call me that, you buffoon."
Lucas laughed out loud as Yaldor didn't know what to think. One side seemed extremely sophisticated but rigid in battle, while the other side had little social awareness but was a monster on the battlefield.
He didn't mind, it only entertained him more. While being on the rougher side, it didn't mean he didn't have any questions.
"Hey Yaldor, who the hell raised that Alastor bastard? He's way too smart to be just a few years older."
Asta shook his head, knowing that wasn't the right question to ask, but Yaldor simply smiled. "I can't say much, especially since you're in a contest with your fellow siblings, Astaroph, even if we're stuck here. All I can say is that Alastor isn't really that intelligent."
Lucas' face couldn't be more frowning. He beat both Asta and Lucas back in the subspace during the banquet, yet he wasn't smart? Writing it off as complete nonsense, Lucas stopped asking questions.
Ten years went by in a flash, while only a few months back in Sabaoth, Lucas and Asta had grown a ton in the time they spent with Yaldor. Just being near him allowed them to progress a lot.
"Well, I believe it's time for us to leave, I don't think they'll last much longer without us," Lucas said with a hint of predication of what awaited them outside.
"Indeed, there's a high chance Isale will have attempted to grab Agatha by now. I hope that what you said about that Galen fellow is right."
"He's strong enough to handle most Rank 2 mages."
"And you know that's below the lowest requirements."
"Hey, you agreed with having Agatha or her coin being taken so you could rescue her and appear as a hero."
"Only after you kept pestering me about it. I wouldn't want to see her harmed in the slightest. But I agree that this is the fastest way to get her to completely rely on me."
"Then let's get out of here."
Lucas and Asta had figured out the answer to the riddle a long time ago, they just kept it to themselves. In order to take advantage of not only this space and the extra time, but also of Yaldor. Squeezing all the information out of him, and using him as a training dummy, Lucas reaped great benefits.
Staring at the riddle, Lucas reread it for the last time.
You've walked the edge of every tree, mapped the winds, named every sea. You've searched the ground, the stars, the sky, yet missed the place where answers lie.The door is here, but cannot be seen, until you look where you have been.
What must you do to leave?
Taking a step closer to the obelisk, he placed his hands on the pillar. "The answer should be something about turning around. Symbolically, you have to face your past," his eyes widening, the words on the obelisk lit up slightly.
Asta instantly spread his willpower, covering almost the entirety of the subspace, finding nothing had changed, not an exit in sight. Shaking his head, he came up with his own conclusion, "Do we have to actually face it?"