The underground area expanded a few dozen meters in each direction.

Because it was a natural cave, the floor was uneven and puddles formed in some areas, and the ceiling became lower the more you walked to the right.

And even though sunlight didn't reach the cave, Xan could see the whole cave thanks to a light sphere floating in the middle of the area.

As Xan neared him, Rad stood up before placing his notebook on his sitting chair.

"We are going to start with the basics of martial arts. Have you read all the notebook I gave you?" Rad asked.

"Yes, I finished it a few days ago." Xan happily replied.

"Great, then you already know the main principle behind martial arts," Rad said as blue light began to cover his arm." Using energy to coat your body or weapons can increase their physical qualities such as resistance or sharpness."

Rad took a stone from the ground and slowly stabbed his index finger as he talked.

"The more energy you use, the greater the effect you will get." He said as his hand's shine began to increase, and his finger sank faster into the stone." But using non-elemental energy is just the first step into the world of martial arts. By using other energies, you can do things that would be impossible otherwise."

With those words, Rad's arm began to burn slightly, which made the stone gradually redden.

"For example, using fire-energy can increase the temperature and create fire out of nothing. Each energy type has its characteristics and properties, making them useful in different situations. Usually, one would start choosing one and mastering it to a certain degree before moving on to learn how to use another energy type. Still, some prefer to continue honing their skills, reaching great mastery that would compensate for their lack of diversity." Rad explained as the fire in his hand gained intensity.

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"And how do I know which energy type I should learn first?" Xan asked curiously.

"Once you learn how to defend yourself, you will know which areas you lack or which you should potency and decide based on that. We already know that you are more agile than strong, so you could go for something that could make you even faster, like air or lightning energy, or make up for the lack of thoughtfulness with earth-energy. Whatever you choose at the end, there is only one thing you can be sure of: you will have to learn how to control corruption, and that's the hardest one." Rad said as the flame on his hand turned black, turning the stone into ash.

"Corruption is also an energy type?" Xan asked, surprised.

"Even though corruption behaves differently from the other energy types, it is still one. And it is mighty if used correctly, but it can also be risky for the user and others."

"Well, like the others, right? If you use too much fire-energy, you might create a fire that consumes a whole city." Xan said.

"Yes, and no. Corruption can empower others' energy properties while giving them new ones. Using a small amount of corruption can increase the strength of an attack by a large margin, but if you don't use it properly, it might end up staining your dantian, body, or mind. Your body will mutate and deform. Your dantian will not contain non-corrupted energy anymore, marking you as a cultist for life. And your mind will become unstable over time until you become a salvage beast that only wants to spread the corruption further." Rad explained as black light expanded from the fingertips toward his arm before retreating to the finger again." Of those problems, the easier to solve is the one with your body which can be solved by learning how to use life-energy or having someone use it on you. That's why I asked you to focus on your mind and dantian."

"What exactly do you mean by using it correctly? How do you know if you are doing it wrong?" Xan asked, concerned.

"When people learn to use corruption, they start with minuscule amounts to learn how to control it. The most common mistake for newbies is to use too much at once, losing control over the energy and making it rampage. That's why you should try to stay as calm as possible after you make your first pact. Most kids your age who start dealing with powerful entities become slaves of their power." Rad warned Xan.

"Pact? It isn't too early for that?" Xan asked with his eyes wide open.

"Well, if you want to increase your cultivation speed and proficiency in using corruption, you must sign pacts with some demons. And the sooner you do it, the better."