The old man took a step back from this battle he was fighting with Cerberus. It didn't seem like just slashing at it the whole time would end up working out well for him considering that Cerberus would always just keep on growing and growing in size.
Eisen tried to shrink down again and hack at Cerberus to see if it was going to shrink down again, as if trying to match the old man's size, but that seemingly wasn't the case. And then, Eisen understood the 'metaphor'.
Cerberus was basically an incarnation of Gluttony, or rather, the concept of 'Hunger'. The more you tried to get rid of it or supress it, the stronger it would grow. But what could he do to beat this monster then? What could Eisen do to beat it? He couldn't just 'accept' it somehow, since that would mean he had to be eaten up by it, and that didn't seem like a pleasant experience.
As Eisen was thinking, he noticed something else. And that was that Cerberus was starting to devour everything around it, including the materials that the castle was built out of. And in response to that... It actually shrunk down. The more it was eating, the smaller it was getting.
"Relieving your hunger can damage your surroundings, or something?" The old man thought, but maybe he was thinking too much into the metaphors that this place presented. But at that point, Eisen got a pretty good idea at what he could do.
He just had to Overfeed cerberus. Luckily, Eisen had a number of pretty interesting items that he could use for that. The old man opened his item storage next to him and shrunk down to the smallest size he could so that he could squeeze in there properly. After a few moments, Eisen managed to find the item in question.
"What are you doing? You just gonna let Cerberus run rampant within this whole realm?" Satel asked, but Eisen immediately shook his head, "It's not like it really matters, does it? But you see, I have a pretty good guess at what kind of creature Cerberus is now. If it's damaged, it's going to turn into that three-headed worm and keep growing in size more and more, as if its hunger is growing. To relieve that hunger, it eats to get back to its regular form. But I doubt I'll be able to really kill it with regular attacks either way. So I'm just taking my time to find a good way to do both of these things."
Satel tilted their head to the side, confused at what the old man just said, "What do you mean 'both'? Do both of what?"
Eisen let out a deep sigh, "I'm going to both damage it and relieve its hunger." The old man said, "Since I only really need volume for that, I think I have the perfect item." Eisen pointed out with a smug grin on his face. He held a small, fist-sized metal orb in his hand that had enchantments carved onto its outer surface.
Satel seemed pretty curious, but as Eisen was about to return to battle, the Guide-Devil held back and just kept floating at a safe distance away from both Eisen and Cerberus.
And then, the old man pushed a small pulse of mana into the Orb he was holding. It started to glow in a bright light, before an exact replica of the orb he was holding was created magically. It wasn't a high-quality item, and it was relatively easy to break, but it was enough for Eisen's purposes.
The way that this item worked was relatively simple. It was using Eisen's 'Blazing Core of the Mountain' element to create the metal base, and as it was being created, the carvings on the outside were created as well, and were at the same time acknowledged as proper enchantments.
On top of that, these orbs had a magical array that was connecting them. So if even one of them had mana infused into it, the enchantments would react according to the old man's will in that moment. He could make one of the orbs create another one, or he could make all of them create a new one simultaneously. At the same time, pushing mana into the orb would allow him to close to instantly repair any damages that were done to it.
And at last, the final function of these orbs was simple. They could either explode, or create sharp spikes on their outside. Eisen figured that both of that might be something to invest in somehow.
Either way, for now, the old man needed a good angle, so he threw one of the two orbs he was holding down at Cerberus and had it create spikes in the middle of the drop. Soon, it stuck to Cerberus' skin, and before the monster was able to regenerate these wounds and push the orb away from it with that, the old man made the orb explode.
This was enough damage to get the attention of Cerberus back, and the monster looked up at Eisen with seething anger practically pouring out of it, although Eisen wasn't sure how he knew that, considering that Cerberus couldn't make any facial expressions.
But that didn't matter anyway. Now that Cerberus was looking at him again, Eisen quickly threw three of the orbs down the three worm-maws of this monster, since he wasn't aware of its internal-structure. It could only have one of the maws actually lead to a stomach, or it could have three separate stomachs. Eisen wasn't entirely sure, so he threw it down all three possible ways.
And the moment that it rolled down Cerberus' throat, Eisen pushed his mana into the Orb he was still holding, trying to affect only the other orbs. He was trying to make the orbs repair themselves at a pace quicker than they were able to be taken apart by Cerberus' stomach acids, and at the same time had them create new Orbs immediately. And then, each of the new Orbs created a new Orb as well. With every single pulse of mana, the amount of Orbs inside of Cerberus doubled. And at some point, Eisen didn't have to concentrate on repairing the orbs anymore, since he would be able to instead focus it all on just doubling them to feed as many orbs as possible to Cerberus, while still increasing the amount of orbs in it, in the end.
Soon, it reached the point where Cerberus was slowly losing its HP just because of the pressure that the Orbs inside of it were creating.
It was feeding on the metal orbs and shrinking, but the orbs themselves didn't allow it to shrink beyond a certain amount. This damage caused the Cerberus to start growing again, but at the same time, it was feeding on the orbs and shrinking. Like this, Eisen was already able to establish a way to cause steady damage to Cerberus. But that wasn't all.
By now, Eisen was able to see that Cerberus did indeed have three different stomachs, each connected to a different mouth and head, so he tried a couple of things out. He made all the orbs in one of the stomachs create spikes, to start out with.
It did damage the Cerberus quite a bit, but its generation was still nullified by the fact that there was enough food inside of its body to soothe its hunger. But at some point, the Cerberus wasn't being particularly damaged by the spikes anymore, just because its flesh basically grew around them. So, he got rid of the spikes and instead did something else. In that same stomach... He made half of the orbs blow up.
In an immense explosion, the shockwave of which hit Eisen's body and even pushed him back a bit, a third of Cerberus' body was destroyed and its pieces were splattered all across the area. This caused it immense damages, but it wasn't regenerating its health yet, not until its body was put back together, just like Eisen thought.
But the best thing was... The same thing could be said about the other parts of Cerberus' body. It was fully concentrating on regeneration that part of its body that it stopped trying to fight the orbs inside of its other two stomachs as much, on top of giving Eisen the chance to attack it.
Before now, it was able to regenerate its body instantly, so Eisen really didn't have the chance to damage it all that much, since it didn't need to concentrate its regeneration on one place. But now, it did.
Eisen swung his blade toward Cerberus' body and cut it up into pieces. Pieces that weren't regenerating at as quick a pace as Eisen thought. With a broad grin after confirming thjs, the old man flew away again, pushing mana into the orb he was holding. And then, he made half of the orbs inside of each of the two leftover stomachs explode as well.
Like this, in a huge explosion that caused even Eisen to be covered in some flesh and blood, Cerberus completely blew up. Even though it was now only a thing in the form of large chunks that were trying to put itself back together, Cerberus still wasn't dead and had a third of its health leftover.
But that's where the rest of the orbs came in. He made them each create another orb once more, and made sure that the orbs spread out properly, mixing in with Cerberus' flesh as it was regenerating. And while this was happening, Eisen was blowing up a couple of the orbs wherever there were larger chunks of flesh gathered.
Like this, the old man was able to shave down Cerberus' health to the point where it only had about 10% of it left. Since he thought it would be a waste not to do this, on top of being dangerous in case any other mortal ended up here in this spot at some point, Eisen told Satel to move away with him, and then pushed his mana into the orb he was holding, making literally every single orb, beside this one, blow up.
A few moments later, the castle had been turned into a crater, and there was no trace of Cerberus left anymore.
And Eisen even had the notification pop up in front of him that told him he beat this challenge that was given to him.
It most likely wasn't the way that the God of this place, Gluttony, intended on having Cerberus be killed, but Eisen didn't really care about that. He did it his own way, and he was pretty happy with the way everything turned out for him.