Aku had been quite clever.
His strategy was simple: first take a hit and regenerate to bait Bīng Xuě into imposing a taboo on regeneration, and that way ensure he could deal irreparable damage.
Now, how could he hurt him?
It was straightforward. Just as he had absorbed the energy from the cursed marks on his body, Aku absorbed the negative spiritual energy from Bīng Xuě in the area he was striking.
A theory that ended up working.
Aku managed to strike Bīng Xuě and damage him, releasing so much heat that part of the nervous system in his face was charred, causing him to feel no pain there.
For Aku it was a victory, however Bīng Xuě didn't seem shaken by having taken damage. Quite the opposite.
"Heh... hehe... HAHAHAHA!" a wild laugh escaped his throat.
It was the first time in a long while that he had felt fear.
However, fear is a fundamental part of a battle.
He had come to understand that after several fights. He had faced entire kingdoms without receiving a single scratch.
But the fun disappeared if you couldn't feel pain.
Bīng Xuě had realized too late why that [damage nullification] was a curse.
He had sought strong opponents to have fun again, yet until now he hadn't found anyone capable of doing more than a scratch.
But that had changed.
Finally there was an opponent worthy of him, and Bīng Xuě wasn't going to waste this opportunity.
The hero forcefully expelled a powerful purple aura.
The cold began to increase while the ice and snow in the surroundings turned purple.
Temperatures were starting to approach absolute zero in certain areas, however Aku was unaffected.
He manipulated the temperature in his own body without even needing to use azoth, simply preventing his body heat from escaping.
Normally an object cools because it interacts with a colder one and both attempt to reach thermal equilibrium.
However, Aku made his body release the minimum possible amount of thermal energy, preserving the heat within him.
Bīng Xuě took a firm step. The frozen grass beneath his feet crunched as he launched himself at Aku.
The demon king was ready and met Bīng Xuě head on.
Both began exchanging blows in an incredible martial display.
However, Bīng Xuě seemed to have the advantage in close combat.
His martial arts were more fluid and his technique more refined, demonstrating his clear superiority in experience.
"Is that all!? I thought someone capable of hurting me would put up more of a fight!" Bīng Xuě mocked as he kept attacking.
Aku didn't respond. He kept extending more neurotransmitters through his body to improve his reflexes, though it seemed useless.
However, he was paying close attention to every move his opponent made, trying to only take hits on his armor while studying his opponent's style.
"Boring!" the young hero shouted as he grabbed at Aku's armor.
Bīng Xuě managed to grab the piece of armor he had cut earlier when he severed Aku's arm, using the gauntlet to slap Aku as he spun and launched a kick at his solar plexus.
The demon king acted quickly, putting his hands in front of the kick and catching it, blocking the attack.
Aku twisted his wrists, trying to throw Bīng Xuě to the ground, but the latter pushed off with his other leg and spun in the air, landing a kick to Aku's face in the process.
The demon king staggered backward, when suddenly all his instincts fired at once.
Both the palm of his hand and his cheek were in danger. Bīng Xuě had taken advantage of contact with bare skin to induce necrosis in the cells of the affected areas.
The cells were dying individually from the cold in an instant, spreading a lethal death throughout his body.
Aku acted fast and quickly shed the skin from both his hand and his cheek.
Losing even two fingers in the process.
"Ha! So that was all you had!" the hero laughed as he pointed his fingers at Aku and long ice stakes shot from them.
Aku acted fast, creating a heat wave around him that evaporated the ice projectiles.
"Tch, raising the temperature is [Taboo]," Bīng Xuě ordered as he manipulated the steam to freeze again.
This was a problem, because he could prevent Aku from manipulating temperature.
However, the boy already had a solution.
He quickly propelled himself using the condensed steam as a smoke screen to accelerate toward Bīng Xuě using the full force of his legs.
Before the hero could react, Aku had launched himself at him, driving his fist with full force into his solar plexus.
The force was immense, enough to shatter his ribs, but the most painful effect was something else.
Using his randomness manipulation, Aku forced the ionization of the matter he was in contact with, causing its structure to break down.
The cells in his body began dying in an effect similar to the necrosis Bīng Xuě had tried to use against Aku earlier, but based on different principles.
"Thanks for the idea," Aku said as Bīng Xuě was sent flying backward again.
The hero spat blood, feeling an indescribable pain that was making it nearly impossible to think.
It was clear who had lost.
However, before the demon king could finish him off, the air roared intensely in the distance.
Aku turned in surprise, watching as a column of crimson and white energy joined the sky and the earth.
Who was behind that incredible display of power?