"As you all know, there are three spiritual forces," Arima stated. "There’s aura, mana, and killing intent."

"We'll start with the aura, which constitutes the main topic out of all three. The aura represents an individual's overall strength. It's established based on many things; your mental fortitude, your life force, your age, your physical strength, and even your soul."

"It's really what you can call the manifestation of strength. The aura can take numerous forms. It can simply be spiritual or have a physical property. Some talented people use their auras to fight, but that's not everything; you can do a lot of things with your aura. It's basically an extension of yourself. You don't lose anything when you use it, no mana nor mental energy."

Arima said and then raised his hand. A faint and transparent light appeared above his palm. He moved his finger and pointed it around the class randomly and the blue aura followed. He then clenched his hand and the aura became a fast projectile that made a hole on the floor.

"That's why it's easier to restrain people weaker than you with your aura," he resumed as he repaired the ground at the same time. "Simply because that way, you won't have to spend your energy for nothing. It's even better than neutral magic from this aspect. The aura is also something you use to subdue, manipulate, and control magic and its mana whether it is yours or the enemy’s."

"Of course, the aura is something you all know perfectly about since you were born. But people still can't use it in an efficient way. I want you to keep in mind that your aura is a valuable asset you can rely on. When you stumble on a certain situation where it could prove itself useful, don't forget to use it. It will become an automatism if you get used to it."

"The next one is the mana pool," Arima followed. "As you all know, the mana pool does not represent your mana storage only, but the term also refers to your mana’s quality and density."

"The mana pool resides in the soul and its size often depends on the latter, as I said before. The size is one thing but the quantity of mana is another. The size of the mana pool is determined at birth, but the quantity can only go up with training."

"You can have a recipient but you can't make use of it if you don't pour something inside. That's the same concept with the mana pool and mana itself. There are also cases where people can't even completely fill up their mana pool during their entire lives."

"Another thing I need to talk about is magic circuits. Magic circuits are what allow us to gather mana in your soul to cast spells," Arima paused and smiled. "If I told you I was born in a place where there were no magic circuits, would you believe me?"

He said and his students looked at him in confusion, they had never heard about a place where there weren't any magic circuits.

But they all believed in their teacher and nodded. Arima chuckled. "And that's true. The place I was born in didn't have any circuits. In that place, since magic circuits were inexistent, I couldn't gather any mana and couldn't use magic."

His students were still a bit lost. They didn't understand why he would bring that up so suddenly. Arima smirked at their reaction. "That's why I can do this," he declared and snapped his fingers.

The students felt a strange disturbance going through them and then felt dizzy for a moment. Night and Karma weren't an exception, but they knew what it was. Only Lanya was unaware. Arima rubbed his temples a bit and got rid of the dizziness in a few seconds. He then smiled at his students.

"I just severed every magic circuit in this classroom," he said and the students’ eyes narrowed. They attempted to gather mana but couldn't no matter how many times they tried. They could only feel the mana they had already stored in their mana pool.

"When you're cut off from the magic circuits, you're unable to retrieve spent mana. If you ever run out of mana in that state, you'll become a simple human unable to use magic," Arima explained and everyone looked at him in shock and anxiousness because of their current lack of circuits.

"Don't worry, even I can't cut definitely your connection with circuits like that. I can only do it temporarily. If I don't do it again, it will come back naturally with time. I didn't use a strong wave right now. It should be back by the end of the period."

"Of course, this technique has huge downsides. I can't restore the connection willingly and it affects a zone around me, and I can't escape it. And since the mana inside the mana pool remains, unless your opponent is weakened, this is useless. But it's interesting to mention that you can use your aura in that state," Arima said with an insouciant smile.

“Well, there’s also a way to exploit that concept and prevent someone from using magic by ‘contaminating’ the mana inflow instead of cutting it. But well, the disadvantages are exactly the same.”

The students didn't know if they should be awed that their teacher created this technique or embarrassed that the downsides were so obvious.

"Well, I'll teach you how this magic works later. I'll skip to the density and quality of mana. To cultivate quality, which means the efficiency between mana used and the result of the magic cast, the key is unpretentious meditation. You need to clear your mind as much as possible and get rid of every ‘bad thought’."

"Now, the density of mana is a special thing. Density means the quantity of mana you can compress together to take the less space possible in your mana pool. Usually, people who don't have a big pool choose to increase their density to be able to store more mana. The way to improve that is by slowly training your mind and soul to compress as much mana as possible."

"That was all for this spiritual force. The next one is, of course, killing intent. You all know what it is. The manifestation of murdering impulses. Of course, I won't show you mine, I don't want to wake up and alarm the entire continent," Arima said casually and his students felt very awkward because of the passiveness of his tone.

"To be honest, you can't do a lot of things with killing intent. The only use you can make of it is basically scaring your opponents or surprise them in a fight. But unless your killing intent is strong enough, it's ultimately useless. The only way to increase your killing intent is by spilling blood. Well, not necessarily humans, but if you just go around killing beast and monsters, your killing intent will never be strong enough to perturb a human of similar strength," Arima said and everyone nodded.

"Killing intent can also be used as a catalyst for magic theory. Actually, the deadliest magics unavoidably have killing intent infused into them," Arima sighed after he finished.

"Obviously, all of this is written in the books I gave you. You can look into it later. Now, it’s time for the main focus of today," Arima announced. "About two weeks ago, I coincidentally discovered a new magic, or to be exact, a new concept of magic theory."

"Tell me, what do you think about when I say fate?" Arima suddenly inquired and his audience was stunned for a moment.

In the end, the regular student model, Ofia, raised her hand awkwardly. "Our destiny…I’d say? Our future actions and how we will live and develop. But, usually, fate is considered inevitable; destiny which we can’t change."

“What about luck?”

“Eh?” Ofia was taken aback by the quick reply and tilted her head. “…In one sense, it’s identical to fate. It’s something we cannot predict but it’s also something we cannot escape since it comes to us naturally.”

Arima smiled and nodded. "Correct. You perfectly explained it. Fate and luck are things connected to our future and intricately associated with our every success and accomplishment.”

“But both of them are concepts we cannot alter in any circumstance. Fate is something that was decided for you. As for luck, it’s the root of the latter. There are some smart people trying to say that luck is only an idea of cause and consequences, but luck is certainly not something you can plan or produce by yourself."

"If for example, one day, you suddenly crouch for some reason and then avoid a critical attack, you won't uphold that you survived because you were so skilled that you dodged the threat without sensing anything, right?"

Arima smiled wryly and his students could only agree when it was put that way. There wasn’t even a way to refute that.

"The reason why I'm telling you this is for the presentation of the magic I want to teach you about," Arima explained. "That magic, I named it 'Libra'. Not 'Libra magic', but the 'Law of Libra'."

When he said the name, everyone started assessing it, trying to find any kind of relation between luck and Libra, the Goddess of Fairness and holder of the 'balance'.

Arima smiled at them. "Have you heard about the luck theory? Simply said, luck is something you accumulate during your life when you feel positive, make good deeds, feels fulfillment, when you achieve something, and so on.”

“Then, when you are lucky about something, the amount of luck you’ve accumulated will regress depending on how significant the fortune your luck brought you. But, if you ‘push’ your luck, you risk to fall into a negative state and accumulate what you call bad luck."

"My magic is directly related to that concept," Arima declared and took out a shining gold coin from his storage. "If I flip this coin, I have 50% to either get heads or tails. But, in the end, your luck will determine the result,” Arima added and started chanting.

"[Qui vocat Lex Libra] (I summon the Law of Libra)."

"[Expende verba mea et iudicia mea imperium] (Weigh my words and execute my command)."

"[Judicium, Quod Libra] (Execute, The Balance)," he finished his incantation and the coin glowed for a second.

He looked at his students. "Look carefully," he said then put the coin on his thumb, preparing to flip it. "If it lands on heads, the coin will duplicate. If it is tails, I'll be hurt," Arima affirmed and tossed the coin while closing his eyes.

The students couldn't even consider what Arima had said before the coin fell back. He caught it with his right hand and put it on the back of his left, covering it.

He opened his eyes and slowly uncovered the coin. It was tails. Instantly afterward, the coin shined and blood suddenly dyed it. The students exclaimed in shock and worry. Arima's palm was deeply cut and blood kept gushing out.

Arima shrugged and waved his hand to appease his class. The cut healed within ten seconds after that, which was actually really strange. For Arima, healing this kind of injury shouldn't even take three seconds.

"As you saw it, I was unlucky and got tails," he uttered after healing his hand. At that point, most of the students had understood the principle already. It was essentially a magic made to gamble with your own luck and have a chance to twist fate.

"I think most of you understood it. I made a gamble. If I had won, I would have gotten another coin. But I lost, and I paid the price for my greed," Arima explained and grinned.

"Now, you may be asking yourself; who did I gamble with? Well, this time, I gambled against the ‘world’ itself. I enforced the gamble on the world. In my theory, it was done so by the intermediary of Libra," Arima said and his students were enlightened.

"Of course, this is a new magic theory. Totally 'fresh' and certainly not optimized. You're not obligated to use the same theory as I do, and you can replace Libra with something else if wish so."

"One more thing," Arima continued. "Since now I used my ‘bad buck’, I should have gotten a boost of ‘good luck’. That's what I call the 'balance', which is translated into 'Libra' with the runic language I use. This is the second use of my magic; controlling luck with bad luck, and conversely."

"When you're unlucky, you basically have more chances to be lucky the next time," Arima flipped the coin again, without casting any spell. When he looked at the result, it had landed on heads.

"Finally, there is the biggest strength of this magic which even scares me if it's well used," Arima's voice became more serious and resounded in the entire classroom.