Sect Leader's Rise to the top!

Kai calmed himself down and tried to think of another idea. This was likely to be his only chance seeing as how skeptical the demon sounded. 

Kai felt the insane hardness of the heart and doubted that he could destroy it with one hit. Kai also had no doubts that Jie would impale him to death if he tried anything funny.

"Maybe..." Kai whispered to himself while thinking up another plan.

"Friend lie?...". Jie spoke again in its childish voice.

"Why would this big brother lie?. I was just getting ready! Now then, here we go!". Kai then closed his eyes and focused on the heart.

"Create Sub-Core..." Kai whispered. He had no idea if this would work, but this was his last option. If he could control Jie, then he would gain a powerful weapon. 

=[Create Sub-Core initiated]=

=[System Warning: Designated target is much stronger than the host. Main-core will be absorbed by the target if the host fails]=

"Wait what?...cancel, Cancel!". Kai shouted, but it was too late. Kai felt his Qi rapidly leave his body and flow into Jie's heart.

Kai looked at his status and immediately got worried.

[Qi]: 653 /999

[Qi]: 552 /999

[Qi]: 450 /999

"At this rate, I'll be completely drained of Qi within seconds!". Kai knew that he needed to do something or else he would be dead soon. He closed his eyes and started to rotate the Qi that had just left his body and entered Jie's heart. By exploiting the remaining bit of control he had left, Kai manipulated the Qi using his Rotation Technique. 

[Qi]: 344 /999

Thanks to the Qi-Rotation Technique, the Sub-Core creation process was accelerated, allowing Kai to create a small, yet fully functional Sub-Core within Jie's heart, thus creating a permanent link between the two. However, to Kai's utter shock, his Qi was still being absorbed at a visibly fast pace.

[Qi]: 231 /999

[Qi]: 129 /999

Kai clenched his teeth and started to absorb Jie's Qi back into his core using the newly created link. The process was excruciating because of the disparity in their power levels, but Kai endured. Essentially, Kai was akin to a small bucket of water, while Jie could be compared to a vast lake. 

Kai only calmed down when he noticed that Jie was slowly being limited to only using the connection that Kai had created. This meant the demon could not fully utilize its actual Qi-absorption rate and was instead being limited to Kai's highest absorption rate. 

Kai saw the Qi-absorption slow down thanks to this restriction, making him sigh in relief. However, an instant later, Kai became horrified when Jie started flooding the connection with its own Qi, forcing the connection to grow bigger and allowing Jie to keep absorbing Kai's Qi.

"Dammit, are you trying to kill me?!". Kai yelled while enduring the pain of having his Qi-Connection forcibly enlarged.

"..." Jie did not respond but the tower shook as if giggling.

Kai clenched his teeth and concentrated on his core. He was also trying to absorb as much Qi from Jie as he could to offset this, however, Jie would simply absorb it back and then some.

[Qi]: 35 /999

"Don't think I'll give this easily!". Kai yelled as he started rotating the remaining Qi into his body. Kai decided from that moment on that he would not just store the Qi he absorbed, but instead pumped it into his Qi paths and used it to cultivate. The Qi flowed out of his core and went directly into his body to circulate through his meridians and increased his body's natural Qi channels. 

The upside of this was that Kai was now able to absorb large amounts of Qi from Jie with impunity seeing as Jie wouldn't be able to absorb it back. However, the downside was that Jie could now absorb Kai's life essence directly.

Kai felt his physical body slowly weakening, but endured it with all the willpower he had. With each passing second, Kai absorbed massive amounts of Qi from Jie and used it all to expand his Qi channels, thus allowing him to absorb even more Qi, but the pain of doing this was excruciating. 

Kai was in so much pain that he clenched his teeth with enough force to crack a tooth, causing blood to flow down his mouth. His eyes turned red when blood vessels in his eyes burst, but Kai continued to endure.

As Kai's natural Qi channels widened, his core also started to expand. His previous bucket-like capacity slowly increased to the size of a bathtub, then increased again to the size of a small pond.

While this was happening, Jie was, in turn, absorbing as much life-essence from Kai as it could. The veins in his right arm shriveled up as his arms started to turn skinny and grey, but Kai endured the pain by howling out loud. 

Each second felt like an hour as Kai tried his best not to pass out from the pain. The spire started to shake violently and Kai heard Jie's voice again.

"Friend...stop now...".

Kai ignored the voice and simply doubled his efforts. He didn't know if he was making a dent in Jie's Qi pool, however, Kai kept absorbing the Qi. The more he absorbed, the wider his Qi channels became, thus allowing him to take in even more. 

The tower shook again, but this time, a spike shot out towards Kai. He no longer had any spare Qi to summon his [Primordial Dragon's Scale Armament], so he could only shift his body slightly to avoid his vitals and let the spike pierce through his abdomen, forcing him into the air. Despite the vicious attack, Kai still did not let go of the heart.

Jie shook in anger and tried using the spike inside Kai's abdomen to suck up even more of his life essence. However, to its horror, Jie discovered that it no longer had full control over the spike. Instead, Kai was using the Sub-core in Jie's heart as a conduit to connect to the spike, allowing him to absorb even more Qi out of Jie.

.

"...Jie is friend, Jie is a friend!". The almost panicked sound echoed in Kai's ears. Kai spat a mouthful of blood as his hair fell messily over his face, but he did not respond. All he had was a murderous look in his eyes.

Outside, the survivors watched as the fog started to slowly retreat until it completely dissipated. The spire was nowhere to be seen, but the ground was shaking so violently that everyone thought the place would tear itself apart.

"What's going on...is it retreating or what?". Asked one of the survivors.

Wu Xianhai looked down at the shaking ground with some thought but did not respond. She had no idea what Kai was doing, but she hoped he could keep doing it.

Back within the spire, Kai's entire right arm looked like a dried-up piece of grey meat. This effect was slowly spreading onto the rest of his body, but Kai was unbothered and kept absorbing the Qi. Kai felt his Qi absorption rate increase, making him realize that this must be one of the 'unorthodox' methods that his new manual, [Daemonic Tempest Law] mentioned. Kai was now benefiting from an increased 20% Qi absorption rate.

Jie tried to remove the spike piercing Kai to slow him down, but it realized that it was futile. Jie no longer had control over the black stone spire and would soon be fully absorbed into Kai.

"Jie will remember!". These were the last words Kai heard as Jie's heart flashed with a blinding blue light that forced him to shut his eyes.

When Kai re-opened them, the heart had split into two equal parts. One half was a dull grey color and still in Kai's hand, while the other glowing half quickly flew through a small opening at the top of the tower, then burrowed into the hard ground until it disappeared.

Kai looked down at the piece in his hand and realized that he could no longer sense any Qi inside of it.

[Illusion Demon Heart (Fraction/Inert State)] [Qi 0 /8214]

"Damn that Jie! did it split itself in half and run away?!". Kai yelled in anger, but then noticed the system announcements that made Kai smile with teeth full of blood.

[Congratulations, the host has broken through to the Foundation Establishment Stage!]

[Martial Arts Manual Slots increased to 10]

[Sub-Core slots increased to 20]