A dumb idea I think might actually work

A long time ago, there existed an ancient world. The ancient world was one of constant war, between good and evil, each vying for control of the world. Was this war necessary? Apparently so, for it was the Cosmic Egg, representative of a far greater deity's will, that governed this war. Keeping good and evil in balance, never letting either side win, while letting them get just successful enough to add fuel to the fire - such was the Cosmic Egg's role. It filtered every soul in this world, creating a cycle of reincarnation that kept the status quo in check for quite some time. Even the gods of the world were forced to follow this pattern - in particular, two brothers, Alpha and Omega, were forced to divide themselves as gods of Good and Evil, whose jobs were to foster new heroes and villains for this constant war.
This changed, however, with the introduction of three heroes, named Marcus, Zack, and Jordan. These three heroes were forces of good who were previously unparalleled, and by their hands evil was constantly vanquished. Recognizing this, Omega ultimately confronted them himself, seeking to stop them permanently. However, despite his best efforts, the three defeated him. Just as they were about to strike the finishing blow, however, Omega pleaded them to hear him out. He told them of the truth about their world - of the war, of the Cosmic Egg, of how it was necessary to keep their world alive. When Marcus asked how such a vicious cycle could keep them alive, Omega explained that this cycle was what allowed humanity to grow, as each side would develop history, create technology, allow humanity to advance in order to reach their ideal world, even though this ideal could never be reached. Sickened by this, Zack delivered the finishing blow, making him the first man to kill a god.
With this victory, the heroes knew that the Cosmic Egg, as well as the other gods, would surely do whatever was in their power to defeat them, to keep good from winning. They took the short bit of time they had left, and created a plan - one that would allow them to destroy the Cosmic Egg, and free humanity from what they viewed as a pointless war.
This event would be known later on as The Opening, as the three would single-handed go through whatever was thrown their way to create a path to, and destroy the Cosmic Egg. Using Jordan's magic to create a tunnel to the center of their world, where the Cosmic Egg resided, they defeated just about every mook, boss, and god out there. And, as they finally reached their goal, and defeated Alpha, the god they had once believed in, Marcus delivered what he had hoped would be the finishing blow for the Cosmic Egg.
However, he only ended up destroying himself.
The attack broke the Cosmic Egg, creating a burst of raw, immense Spirit Energy to be released from the Cosmic Egg, and flood into the world from the tunnel Jordan and his friends had created. With this burst of Spirit Energy, every life form was corrupted by magic, creating monsters the likes of which had never been seen. Humanity itself mutated, rapidly transforming into the very beasts they had once slain. Anyone who was actually in the tunnel was completely erased - with the exceptions of Marcus, Jordan, and Zack. The three were so powerful, that their very memory was burned into the Cosmic Egg forever, bringing with it an unusual curse - the three would constantly reincarnate, always as friends, always with recollections of their past lives, but never to reach their former glory as heroes.
The Cosmic Egg repaired itself over time, and when it was back to normal, it decided to purge the monstrous world that Marcus had inadvertently created. With a sudden rush of water, many of these ancient monsters were wiped out. A few survived, eventually leading to the group known in the modern day as The Deep Ones. A new pantheon of gods was born, and they all took it upon themselves to make sure that the world would never suffer like it did when The Opening occurred. Now set on a world made of many islands, the war between good and evil soon resumed, with the gods closely watching how the war went. Unlike the gods of the ancient world, they assisted both sides at once, simply offering incentive to becoming strong and fighting for what one believed in. Sometimes, when the Cosmic Egg chose a particularly strong hero or villain, they themselves would raise their opponent to match them, usually ending in a stalemate between the beings. Such an event happened when Keren and Gwendolyn fought.
However, when they learnt of the Cosmic Egg's next chosen villains, they swore a mistake had been made - for it was the reincarnations of the three heroes, Marco, Joseph, and Isaac. In this scenario, they did all that they could to try and stop them from reaching this potential. And yet, the Cosmic Egg's will won out. They persevered, and became adventurers who were more than capable of fulfilling this role. They even hand-picked a hero, Isaac's brother, George, to try and stop them. But again, this failed. George ultimately ignored their call to help his friend Samuel finally put an end to The Deep Ones.
And, in an even more critical change of fate, the three accidentally stumbled upon the wrong information. Information that the Cosmic Egg didn't intend them to find, even if it wanted them as new villains.
Information about their past lives.
Marco and his allies learnt that there stood a tower somewhere in the world, called the Tower of Babel. This tower was located where the hole that the three heroes had originally created, in an effort by the gods to hide it by transforming it into a massive structure, which grew high above the waves as well as below. The three went here to claim the pin that held the tower together, Kusanagi, and reopen the path to this tunnel, which they decided to dub Hell's Gates.
As if attempting to predict them, the gods sent George, Samuel, and all their allies to this tower, warning them that a great evil would rise soon, and that to prepare, one of them must wield the sacred sword, Kusanagi. When they reached the top, however, the two ended up arguing over who should wield it, buying enough time for Marco to jump in, and take the sword for himself. As he did so, he proclaimed himself the Necromancer - after all, it would be he who would revive the hope that the ancient world once had, by finally destroying the Cosmic Egg once and for all.