Can I finally exit?

After a hundred thousand years of fighting, Zero still can't find how to exit the abyss. He tried different kinds of weapons and mastered them for entertainment. He even masters how to blacksmith. His body didn't even age a little bit because he can freely manipulate the mana in his body so that he won't look old. After a million years he encountered many new species like Spirits, Mutated Demons, Undead, and Fox with hundred tails. Zero killed all of them because every time he asked how can he exit the abyss they all have the same answer "It's impossible". He just keeps moving forward to find the answer on how can he exit.

An unknown amount of time has passed he finally finds an answer from the monsters he encountered. The one he's talking to is a Spirit who lived for eons. Zero asked "how can I exit here?" the spirit answered while trembling in fear "there's only one way, you need to kill the owner of this abyss". The spirit is full of blood all over its body with many holes in its body. Zero asked

"Where can I find him?".

"At the end of the abyss you will see a big castle, that's where he lived. Y-you d-don't tell me you're trying to kill him? It's futile you don't stand a chance against him."

Zero laughed

"Hahaha. If that's the only way to get out of this hell, I'll kill him. I can't stand anymore to live in this filthy place you know. If I die, I die." "I'll let you live thanks for the information." Zero disappeared insight of the spirit. The spirit sighed relief and muttered

"Can someone finally clear this place? Even with the combined power of God and Demon King, they can't last here for a thousand years. I want to be free too." The spirit sighed before it vanished.

Zero finally arrived in front of the castle. The castle is big but it looks very old. He entered and he saw a throne in front of him. He can't find anyone so he extended his mana to feel any presence but he can't find anyone. "Did that spirit trick me? I'll-" while Zero is muttering to himself he noticed a presence. He finally saw someone sitting on the throne. He can't see it clearly because the castle is dark. The man on the throne spoke with a deep voice "Can you satisfy me?". Zero answered with a smirk "Why don't you come down to know it yourself?" The man on the throne disappeared and appeared in front of Zero. Zero finally saw the face of the man. His body is composed of the scales of a dragon, the tails of a fox, the body of an orc, the aura of spirits, and many more monsters that Zero can't identify. The man said, "I'm terrifying right?"

Zero answered, "Yeah, you're terrifying because you're too fucking ugly". While Zero is trying to be calm, he can feel his heart beating faster. He can feel the very absurd aura that this man is trying to suppress. Not only his mana but Zero can't keep up with his movements. The man said with a laugh "Hahaha I know I'm scary, but I know I'm the strongest too" the last part is said with a serious tone. Zero said, "enough of the talk let's start the business". Zero unsheathed the sword that he created while he was bored exploring the abyss. His sword color is black and it resembles a samurai. But the blade of his sword is slightly thicker than a samurai. The color of its grip is dark red. It's made of the hardest metal that he can find in the abyss. The man asked "what's your name?" Zero answered, "just call me Zero. How about yours?". The man said, "they call me Greed".

Zero disappeared and tried to slash Greed.

Clang!

But Greed's body is very sturdy. Zero immediately retreated. Greed shoots a beam made of darkness to Zero.

Boom! The castle trembled but the castle is unscathed.

Zero avoided the beam of darkness. Zero said with a smile "let's stop holding back now". Zero unleashed his mana while Greed did the same.

Zero asked, "I forgot to say that I'm here to exit the abyss how can I exit?"

Greed answered "If you kill me, this world will vanish with me. To be honest I can't leave this abyss because that damn God sealed me here while I'm in my weakest state. I can't find a way to remove the seal. So I strengthened this world by absorbing all the mana and monsters that I can find and that's my ability [Devour]. I can't devour the seal because my power is incomplete. And I can feel to you that you have the remnants of my power."

Zero asked, "Why didn't you find the remaining power by yourself?"

Greed answered " I told you I'm sealed and this castle is my seal. I can't get out of this castle. But I can freely absorb mana outside the abyss so I did is to spread my mana in this world so monsters will be created from my mana. I also somehow managed to transfer monsters from different worlds. So I will only need to do is to wait who can conquer the abyss that can find the remnant of my power and wait for him/her then kill him/her then devour him/her then my power is complete."

Zero said "So that's it, but I'm sorry I won't die here" Then Zero and Greed continued to clash with each other.

Clang! Clang! Clang!

After fighting for a month both sides are exhausted. Zero said while yawning "let's end this I want now to sleep". Greed didn't answer but he raised his right hand and a black orb appeared trying to devour Zero. Zero can feel the ominous power that's coming from Greed's right hand. Zero said with a smirk "Hehe. I know you know I can do that too." Zero raised his hand and a bigger black orb appeared and said, "So let's see Am I getting devoured or you're getting devoured?". Greed can feel that Zero's power is stronger than him. Greed said, "as expected of my power". Then Zero devoured Greed without any resistance. Greed left without any traces.

Zero muttered

'That's it? There's no trump card at the end? I'm expecting to fight him for a very long time. Jeez, what a waste.'