Martial arts.

The moment he started cultivating his body began devouring the spirit energy like before. But after several hours his body began to feel bloated, and he had to stop. If he was a cultivator from the Heavenly Alliance, he would spend the next few days resting as his body got used to the spiritual energy inside him. Since he was a demonic cultivator, he wasn't going to do that. He got up and left the inheritance room and went to the center of the tomb. He held his right hand before him and a small green flame flickered to life.

This green flame was soul fire. It was an odd fire; it could be hot, or it could be cold. If it was hot, it could burn flesh and melt bones, but if it was cold, it would leave the body unharmed and burn the soul. It was the signature flame of the Soul Controlling Sect, ad all those who saw it, feared it. 

After staring at the little flame in his palm for a few seconds, Xavier pushed his hand out and willed his spirit energy to feed the flame. The small little flame grew, it extended five or six feet in front of him and released a hissing like scream. The bloated feeling he just had was gone, it was replaced with the feeling of the spiritual energy in his body being quickly drained. In a little less than a minute he was feeling empty but continued for a few seconds more when he began to feel dizzy. When he felt that first wave of dizziness, Xavier immediately stopped his spell and sat down to cultivate.

By doing this over and over again, he was forcing his body to adapt to spiritual energy. Doing it this way decreased the time he needed to wait till he could break through to the 2nd layer and begin the next level of body cultivation. But this speedy way of doing it did have its dangers. If a novice cultivator overdrew the spiritual energy in their body, they would risk damaging their meridians, the spiritual energy pathways throughout the body. Even minor damage to the meridians would takes weeks to months to heal and stop a cultivator's progression till they healed, severe damage could end a cultivator's ability to ever cultivate or even death. 

This was not the choice Xavier made the first time, he chose the slow route and waited. At the time he knew nothing about cultivation and spiritual energy, he knew nothing about what it meant to be a demonic cultivator. He had been a fierce martial artist who spent forty years boldly moving forward in pursuit of strength, but when he discovered the cult's cultivator inheritance, he found himself unable to be reckless as he had been, almost to the point of being timid. Unlike last time he had the experience of five and a half centuries worth of experience to be daring.

This how he spent the day, cultivating and creating a pale green flamethrower, then repeating it. By time he quit for the day the speed he could draw spiritual energy in had increased, as well as the amount of spiritual energy he could hold greatly increased, bringing him closer to the peak of the 1st layer. The only downside was this younger body of his, it was unaccustomed to sitting still for so long. His body was still that of a child, it needed to move. Before he woke in in his younger self's body, his younger self was training to be a martial artist. This body spent its days running and fighting from sunup to sundown, and it needed to exercise.

After waking up and taking care of his business outside the tomb, Xavier didn't start to cultivate. He stripped off his clothes and began to practice martial arts. The martial arts practice by the three factions of this continent were limited to mid-tier ranked martial arts, this was to secure the safety of the cultivators that came from the various sects. These martial arts could push someone who mastered them to the peak of humanity, while cultivating pushed humans far beyond what humanity was capable of. Depending on the inheritance, the gap between human and beyond human can start to appear as soon as the 3rd layer or up to the 5th layer. And only those who truly mastered their martial arts could still pose a threat to cultivators.

Which is why Xavier wasn't going to practice mid-tier ranked martial arts, he was practicing high-grade ranked martial arts. High-grade martial arts were made for humans to fight and kill Qi Condensation ranked cultivators and be able to escape those at the initial stage of Foundation Establishment. Anyone who masted this martial art would be able to kill anyone on this continent with relative ease, with only spells and cultivator weapons being a threat to that martial artist. 

Very few cultivators on the mainland practice martial arts, which is why Xavier was able to buy over a dozen high-grade rank martial arts manuals for a few spirit stones. He found it disheartening that the martial arts prowess he spent four decades perfecting was considered worthless, it was just another one of the many disappointments he had when he arrived in the mainland.

His martial arts practice lasted less than an hour, he had only been learning the cult's martial arts for a few months and had limited internal Qi. There were two ways he could replenish his inner Qi, the first was to use the martial arts own Qi method and cultivated his Qi, and the second was to eat nutritious foods and wait for it to replenish over time. Xavier had no intention of spending time cultivating his Qi while he was in this tomb, he was only practicing martial arts to get some exercise. After he left here he would have the time to spend increasing his inner Qi, but for now the ration ball would count as nutritious food and his time cultivating should be more than enough to replenish his inner Qi.

For the next few days, he would practice martial arts before beginning the cycle of draining his spiritual energy before cultivating to replenish it till it was time to sleep. After practicing martial art on the third day, he used the ghost flames to drain his spiritual energy and began cultivating as normal but when he should have been full of spiritual energy, he felt that all too familiar popping sensation of breaking through. He was now at the 2nd later of Qi Condensation.

This meant that today was his last day here, after cultivation a bit more to fill up his now larger capacity to hold spiritual energy, he would practice the next step of body cultivation. It wasn't that long before Xavier was finished cultivating and had stripped off his clothes so the pain could begin. 

When he arrived the rainbow-colored mist within the array was thick enough Xavier couldn't see through it, after he used it the first time, he could see through it but still couldn't read the words on the wall. After the second time he used it, he could read the words on the wall. After this third time there would be very little of the rainbow-colored mist left. As he looked at the thin mist in the array, he found himself disliking the sight of it and decided to fix it before he left the cult. It wouldn't take much effort; he just had to capture the soul of a bunch of recently dead humans or animals and release them into the defensive array in the forest. Since the next step of his plans was to kill a bunch of animals and bandits anyway, he could just kill some more to replenish what he used.

This inheritance had changed his life his first time around and allowed him to live long enough to have this second chance, and this made him feel he owed a debt to this place. He didn't like the feeling of owing, so he would repay this debt and severe any karmic ties to this place.

With his plans set, there was nothing holding him back. Stepping into the array and sitting down he began body cultivation. While the rainbow-colored mist still dulled the pain, it still felt like someone was trying to pull him apart limb by limb. His bones creaked and his muscles strained, but after an hour or so it was over. 

After placing everything in the sword cultivators' bag in the fire worshipper's bag, he packed almost everything he brought here into the now empty storage bag. Then he got dressed, and after stepping out of the inheritance room he sealed the door. He gave the founding ancestor a final salute and headed towards the exit of the tomb. The first time he stepped out of this tomb he was unsure of many things; this time he was sure this the start of great things to come.