Seeing Goku shatter his magic with a single punch, Hades truly became enraged.
"Brat, you are remarkable, forcing me to this extent. Then next, let me show you the abyss of the Magic Way, a realm of magic beyond your imagination!"
Hades struck a peculiar pose, and the magic power within him erupted outward frantically, resonating with the surrounding matter.
"Forbidden Magic: Nemesis, the Heavenly Executioner!"
This was a forbidden spell belonging to the Twelfth Paragraph of the Fourth Chapter of the Books of Zeref, and it was his most powerful magic.
One by one, pitch-black demons slowly crawled up from the ground. Each one contained immense magic power, with strength not inferior to a typical S-Class Wizard. Dense swarms of demons coalesced into an army and flew toward Goku.
Seeing this, Goku charged forward without fear, clashing with the demon army. Unleashing various forms of Ki Breathing, every technique wiped out scores of demons. On his own, he threatened to crush the entire demon legion.
This sight utterly shocked Hades. Every time he thought the boy had shown his limits, Goku would display power far beyond his anticipation.
But despite his astonishment, he did not panic.
"If anyone else cast this spell, they might not be your match, but this old man is different. Let's see how long you can hold out."
With endless magic power continuously pumping out, demons constantly spawned from the ground to replenish the ranks, ganging up on Goku.
Other wizards, even those at the Heavenly King level, had finite magic power.
So naturally, even when using this forbidden magic created by Zeref, the number of demons they could summon was limited. If their magic ran out, no more demons could be created to replenish the fight. Against a terrifying fellow like Goku, they would lose.
However, his magic power originated from his modified Devil's Heart, which could infinitely collect magic, providing him with a continuous supply.
Thus, he could maintain this forbidden magic indefinitely, allowing the endless horde of demons to wear Goku down until he died.
"We are Fairy Tail! Let's go together, everyone!"
Natsu and the others, who had just arrived, saw Goku surrounded by the demon army and immediately began howling to go help.
But after rushing forward for a bit, they saw Goku strike a certain pose. They instantly froze in their tracks and even retreated a significant distance. This reaction elicited a surprised expression from Mard Geer, the Underworld King, who had arrived a step ahead of them.
Originally, he had planned to step in and intercept them, buying some time for Hades to finish off his opponent.
Soon, he understood why Natsu and the others weren't stepping forward to help but were retreating instead.
"Hades, you're very strong, so I'm going to use my strongest ultimate technique too!"
Realizing that no matter how many he killed, the demons were continuously replenishing, the battle-hardened Goku also grasped the problem.
Therefore, he decided to wipe out all the demons in one go and also resolve Hades, the one creating them. Honestly, he had fought very joyfully and satisfactorily today. It was also time to end this battle.
"Total Concentration: Kamehameha Wave!!!!"
Concentrating the vast majority of the Ki in his body into his cupped hands, Goku unleashed the most powerful Kamehameha wave he could currently muster.
A terrifying pillar of energy blasted forth, instantly enveloping all the demons rushing at him.
Every demon that came into contact with the Ki wave was instantly disintegrated into the purest magical particles, and the wave rushed on with almost zero pause, blasting straight toward Hades.
"It's here, Goku's Kamehameha!"
Although this wasn't the first time watching Goku use this technique, every time they saw it, they were still incredibly awestruck.
And Natsu and the others felt that the power of Goku's ultimate move grew stronger each time.
They had immediately retreated just now because they saw Goku was about to use this big move.
Otherwise, if they had rushed forward and gotten mixed into the melee with the demon army, they would definitely have been caught in the blast wave.
"What is this!"
Hades, seeing this technique firsthand for the first time, was also terrified.
Intuition told him that if he were hit, he would die—even with the Devil's Heart, he would still die.
The Devil's Heart could provide him with endless magic power and longevity, but if his original body was obliterated into magical particles, he wouldn't be able to revive.
However, because he had been continuously maintaining the forbidden magic, he was completely unable to dodge in time.
Stopping such powerful magic also required time. Consequently, he could only treat a dead horse as if it were alive, using his strongest dark defensive magic.
"Darkness Magic: Shadow of Eternal Night!"
A massive black barrier appeared in front of him, attempting to block the Kamehameha. Unfortunately, his strongest defensive magic couldn't even hold out for three seconds under the onslaught of the energy wave.
"No!!!"
Hades let out an unwilling roar as he was engulfed by the Kamehameha, his body decomposed into the most fundamental magical particles, dissipating into the world. Hades, Master of Grimoire Heart, deceased!
Goku, who had unleashed this full-power attack, reverted to his normal size and also began to pant heavily.
Clearly, after this blast, the Ki in his body was not plentiful either.
After all, before unleashing the full-power Kamehameha, his battle with the demon army had also consumed quite a bit of Ki. However, with his physical condition, a short rest and a good meal would quickly allow him to recover.
"We won!"
The surrounding observers, Natsu and the others, saw that Goku had eliminated Hades and began shouting excitedly, one after another.
Not far away, Mard Geer, the Underworld King holding his book, hesitated for a moment before choosing to retreat into the shadows. He had thought about whether to launch a sneak attack to eliminate Goku now while he was obviously quite weak.
The strength Goku had displayed was already capable of threatening him, especially that final technique. He felt that even if he reverted to his true Etherious Form, his end would be no different from Hades'.
However, looking at the Fairy Tail Wizards gradually gathering around, as well as Jellal holding Brain, he ultimately abandoned the idea out of caution.
He was worried that Goku might still have the power to unleash that technique again; if those Fairy Tail Wizards nearby were also added, then his chances of winning were not high.
To be able to develop Tartaros to its current state, he was not an impulsive person. Although the three guilds were finished, and all of Tartaros' demons had been killed, none of that mattered.
Because as long as he could find a way to detonate the magic pulse bomb, Face, and make the magic power of this world disappear, then he could rule this world relying on the demons' Curses.
Human wizards required magic power to use magic; once the world had no magic power, then the wizards would be no different from ordinary people. But demons did not use magic; they used Curses, and Curses consumed Ethernano.
Even if the entire world had no magic power, it wouldn't affect his use of Curses. Thus, at that time, absolutely no one in the entire world would be able to pose a threat to him—not even Zeref, who had created them as demons.
It was just that the magic pulse bomb, Face, was held in the hands of the Magic Council, sealed within the bodies of three council members via Organic Link Magic.
This was why he was willing to trade with Hades. Of course, resolving Fairy Tail, the kingdom's strongest wizard guild, was also beneficial for his later plans.
Even if Hades hadn't offered sufficient terms, he would have helped. It just wouldn't have been with this much effort—at most, he would have sent a few demon subordinates over.
Now that Hades was dead, he needed to obtain information about Organic Link Magic from other sources. Compared to dealing with Goku's group, it was obviously much simpler to deal with the council members.
"What's that sound?"
However, right at that moment, he faintly seemed to hear a dragon's roar coming from afar. A black dot was flying toward Tenrou Island at extreme speed, then gradually became clear.
"Could that be... the Black Dragon of Apocalypse, Acnologia!"
Cold sweat instantly burst out on the face of Mard Geer, the Underworld King of Tartaros. As a demon created over four hundred years ago, having founded Tartaros and lurked for so many years, how could he not know of the existence of the Black Dragon of Apocalypse, Acnologia?