The black tomoe merged as they spun, taking on a new form.
It was Gilgamesh's [Eternal Mangekyou Sharingan].
To Sirzechs' surprise, what happened next shocked him.
A thin tear fell from Gilgamesh's right eye.
But it was made of blood.
"Amaterasu."
At Gilgamesh's command, an immense blaze of infernal flames manifested, to Sirzechs' surprise, and collided with the spheres of [Power of Destruction].
The black flames clashed and intercepted the [Power of Destruction]. Sirzechs' power sought to destroy everything while Gilgamesh's flames tried to incinerate the demon's power.
And this led to a stalemate where both were being nullified.
Sirzechs' eyes widened as he saw his [Power of Destruction] being suppressed.
This was the power of [Amaterasu], one of the techniques of Gilgamesh's [Mangekyou Sharingan]. Said to be the highest-level fire technique and the representation of the "Material World and Light," [Amaterasu] is the antithesis of [Tsukuyomi].
A technique that consists of materializing black flames at the focal point of the user's vision. In normal situations, it's almost impossible to avoid [Amaterasu]; however, if the target can move fast enough to avoid being focused on, it becomes impossible to materialize the flames at the desired location. The black flames can continue burning for seven days and seven nights, being impossible to extinguish with water or other normal methods unless the user wills it. The black flames of [Amaterasu], said to be "the fire of hell" and as hot as the sun, burn any material (including other flames) until only ashes remain.
What was previously a physical battle between the strongest Maou and the strongest Hero had become a battle of attrition; the first to tire would lose.
Sirzechs increased the output of his [Demonic Power] and [Power of Destruction] even more as dozens of crimson spheres manifested and advanced toward Gilgamesh, annihilating everything in their path.
Meanwhile, Gilgamesh continued to unleash his [Amaterasu], and using another technique, [Enton: Kagutsuchi], which had the power to shape the black flames, Gilgamesh molded his [Amaterasu] into dozens of black flame arrows and fired them against Sirzechs' power.
The space around them was distorted by the clash of both fighters' powers, the very fabric of reality seeming to be on the verge of breaking under the absolute power of the Hero and the Maou.
However, the one tiring first was Gilgamesh.
Sirzechs had an enormous [Demonic Power] and centuries of experience using his power.
But for Gilgamesh, it was more complicated.
Although he had mastered the use of the [Mangekyou Sharingan], it was rare for the King of Heroes to resort to the power of his eyes.
Due to his overwhelming power, Gilgamesh usually only used his own power or that of his Sacred Gears; it was extremely rare for him to use his visual powers.
And so, using [Amaterasu] in such a large quantity was truly exhausting.
In addition to the large amount of power the [Mangekyou Sharingan] demanded to stay active, plus the cost of [Amaterasu] itself, they also exerted enormous pressure on Gilgamesh's body.
The fact that he possessed the [Eternal Mangekyou Sharingan] only prevented Gilgamesh from going blind, but his body still suffered the damage from using the ocular techniques.
Obviously, if Gilgamesh used his full power, such as activating his [Rinnegan] or [Tenseigan], victory would come easily.
With the [Preta Path] of the [Rinnegan], Gilgamesh could absorb any of Sirzechs' attacks, among other methods.
But that wasn't what the King of Heroes wanted.
Gilgamesh was consciously limiting himself to enjoy the battle more, restricting his power so he could fight for longer.
And that came at a cost. Due to the strain on his eyes from the constant use of the [Mangekyou Sharingan], Gilgamesh was forced to close them for a moment.
And that was the opportunity Sirzechs needed.
Seeing the black flames diminish, Sirzechs increased his [Power of Destruction] even more as dozens of crimson spheres were created and advanced at full speed toward Gilgamesh.
When Gilgamesh opened his eyes, the crimson spheres were already in front of him.
An immense explosion generated by the clash of [Demonic Power] occurred, creating a massive shockwave across the entire area.
Sirzechs watched calmly; he knew this wasn't enough to defeat Gilgamesh, and he also noticed that the King of Heroes seemed to be holding back.
But when the cloud of smoke cleared, what appeared shocked Sirzechs.
An immense golden aura covered and protected Gilgamesh's body, taking the form of the upper part of a human skeleton with a long sword in one of its hands.
That was [Susanoo], the third ability granted to those who awaken the [Mangekyou Sharingan] in both eyes.
The creature covering Gilgamesh swung its sword, releasing an immense shockwave that forced Sirzechs to leap away to dodge the attack.
Quickly, Sirzechs waved his hand, releasing his spheres of [Power of Destruction] against the avatar protecting Gilgamesh.
However, the moment they collided, all that happened was an explosion, and when the dust cloud cleared, the [Susanoo] was revealed to be intact, to Sirzechs' surprise.
Gilgamesh's [Susanoo] was completely coated in his [Divine Power], making it far more resistant than normal.
"That was interesting, Sirzechs, but allow me to return the favor," said Gilgamesh with a wide smile.
To the Crimson Maou's surprise, the energy avatar protecting Gilgamesh discarded its sword, and its hands came together.
And at that moment, the [Rinnegan] manifested in the King of Heroes' left eye.
And then a single technique was announced by Gilgamesh.
"Tengai Shinsei."
After hearing Gilgamesh's words, the Crimson Demon King prepared for whatever Gilgamesh had planned.
However, after a moment, Sirzechs looked in confusion when he saw that nothing had happened and even thought that Gilgamesh's technique had failed.
But he quickly discarded that idea.
The entire battlefield region had been covered by an immense shadow, and looking up, Sirzechs stared in surprise and fear at what he saw.
An immense meteor, twice the size of Kuoh City, was falling over the region.
In fact, falling wouldn't be the best way to describe it, as the meteor was only a few hundred meters above Sirzechs and Gilgamesh.
Sirzechs' expression of surprise turned to Gilgamesh as the [Susanoo] protected him.
"You'll hit yourself too?" shouted Sirzechs, stunned.
Gilgamesh only smiled calmly. "I have several ways to defend myself, but what about you?"
Sirzechs' eyes quickly turned to the meteor falling toward him, and increasing his power, Sirzechs' [Power of Destruction] exploded.
An immense crimson aura burst from Sirzechs' body, this intense aura condensing in the hands of the Crimson Maou as he raised them.
The ground around Sirzechs disintegrated due to the sheer destructive power being released, and Gilgamesh could see that space itself seemed to be collapsing due to the overwhelming power of the Crimson Satan.
Sweat dripped down Sirzechs' face due to the effort of releasing so much power at once, something he wasn't accustomed to.
The crimson aura gathered in Sirzechs' hands as it condensed into an immense sphere of pure [Power of Destruction].
Expanding his power, the pure sphere of destruction advanced against the meteor.
The sphere of destructive power collided with the massive meteor, generating a huge shockwave from the impact.
Although the meteor had enormous destructive capacity, it was still just a massive rock, and upon contact with the immense amount of [Power of Destruction], it was being annihilated.
When the [Power of Destruction] completely consumed the meteor, it exploded, generating an immense shockwave that made the entire battlefield tremble.
Gilgamesh only watched calmly from the protection of his [Susanoo] as he waited for the dust cloud that had been raised to dissipate.
And when it cleared, the King of Heroes saw Sirzechs Lucifer, kneeling and panting.
And that didn't surprise Gilgamesh. The power Sirzechs had gathered in that attack made a God-class being seem like nothing in comparison.
And although Sirzechs had absurd power, he wasn't accustomed to releasing so much power at once; it had been centuries since Sirzechs had used that much power.
Gilgamesh only watched calmly as his [Rinnegan] deactivated.
If he wanted, it would be simple to summon a second meteor, but seeing Sirzechs' state, Gilgamesh thought it wouldn't be necessary.
"That was quite impressive, Sirzechs, but now you have less than half your power. That won't be enough to defeat me," said Gilgamesh calmly.
To the King of Heroes' surprise, Sirzechs stood up while letting out a laugh.
"It's true, even if I had my full power, I doubt I could defeat you normally," said Sirzechs slowly.
Slowly, a crimson aura began to cover Sirzechs' body.
Gilgamesh's eyes narrowed; the quality and quantity of the power were entirely different from what Sirzechs had released before.
The crimson aura began to expand from Sirzechs' body, and the armor covering his body was suddenly annihilated by the power of his aura.
Obviously, that wasn't a normal armor; it had been specially created to contain Sirzechs' aura, and yet it was destroyed so easily that it surprised Gilgamesh.
"To defeat you, I'll have to give something in return," said Sirzechs calmly.
Above Sirzechs' body, an enormous magical circle appeared, and thanks to his experience, Gilgamesh recognized what it was.
"A sealing magical circle?" thought Gilgamesh aloud.
Before Gilgamesh's eyes, the magical circle broke, making Gilgamesh's eyes widen at what he felt.
An overwhelming presence swept over the entire area, a quantity of power so immense that it distorted gravity itself. The pressure of gravity increased hundreds of times over Gilgamesh, making the King of Heroes' eyes widen at the pressure, though it didn't bother him much.
The nature of the energy was identical to what Sirzechs exhibited, but it was infinitely greater, like an abyss of difference, exuding so much pressure that it affected the entire battlefield.
It was as if a black hole had suddenly appeared on the battlefield; the gravitational field around it had become so intense that space-time itself was cracking. The trees around were crushed and turned into mere twigs due to the sheer presence of such magical power.
Even in the face of all this, all Gilgamesh did was slightly widen his eyes at what was happening.
"Gilgamesh..." Regulus' voice emerged, showing concern.
"Yes, his aura is five times greater than before, maybe more..." pondered Gilgamesh calmly.
But an immense smile appeared on his face when Gilgamesh realized what Sirzechs had truly done.
"So you went so far as to sacrifice your life to defeat me, Sirzechs," shouted Gilgamesh excitedly.
As the uncontrollable aura calmed, it was possible to see Sirzechs in the middle of that enormous whirlwind of power, his hair floating as his eyes glowed crimson.
"So you realized? I suppose that's to be expected," said Sirzechs as his power increased.
What Gilgamesh had realized was something simple: Sirzechs had been storing [Demonic Power] since they met for a future battle.
But doing so wasn't that simple. To obtain such massive power, Sirzechs had transformed his own life force into power and was storing it.
But to obtain such great power, Sirzechs had to sacrifice an absurd amount of his life force.
"Even for demons who can live almost eternally, I've lost many years, centuries, or even millennia. Honestly, if I manage to live for the next five hundred years, it'll be a lot," said Sirzechs in a calm tone.
In the face of this, Gilgamesh could only laugh with excitement.
"Hahaha, impressive, Sirzechs. You'd go so far to defeat me?! To kill me?!" shouted Gilgamesh excitedly.
Sirzechs' uncontrollable aura began to gather around his body as he absorbed all the energy.
Seeing this, Gilgamesh increased his power even more. His [Susanoo], which was only bones, began to gain muscles, then skin, and finally armor.
Seeing this, Sirzechs took a deep breath and drew the power within him, just waiting to be unleashed.
The world itself trembled and seemed to scream in terror as Sirzechs' aura grew larger.
In an instant, Sirzechs was engulfed in a deep crimson cocoon, sending shockwaves of raw power reverberating not only through the battlefield but throughout the entire barrier's territory, and perhaps even beyond.
It wouldn't be surprising if even humans, usually oblivious to supernatural events, could feel it at full force.
An entire ocean seemed to have appeared above Gilgamesh and the entire battlefield.
A loud snap drew his attention, and he looked back to the eye of this storm of pure power.
The cocoon began to open, with a red light emerging from the opening, filling the forest with an indescribable otherworldly energy.
Then, with a resounding sound of glass breaking and a blinding flash of red light, the cocoon was torn apart, sending a massive shockwave that felled forests and destroyed mountains merely with its presence.
In the space where Sirzechs and the cocoon he was enveloped in had been, something appeared.
It had the form of what seemed to be an extremely dense cluster of [Power of Destruction], grouped in the vague shape of a human.
But it was much more, far more than anyone could comprehend.
Thus, it could only be described as something, for there were no words in any language, living or dead, that could truly describe what was there.
"Feel honored, King of Heroes. This is the first time in three centuries that I've assumed my 'True Form,' the only other to have the same honor was Rizevim Livan Lucifer."
The thing spoke in a horrific mockery of Sirzechs' voice, crystal clear even above the noise the world itself made as it trembled with the force of that thing's presence, the space-time of the area distorting as it lost its cohesion.
The sounds that normally came from the throat of the Crimson Lucifer were gentle, soothing, and even melodious, befitting someone who succeeded the Devil known as the Seducer of Humanity.
The voice of this thing, if it could be called that, was cold, dark, ominous, filled with a supernatural power that sent shivers down the spine with every sound made.
It was something that shouldn't even exist.