Side Character Transmigrations: The Final Boss is No Joke - Chapter 8

He rose from abjection and achieved eternity in glory.
He embraced the prettiest beauties and killed the strongest opponents.
He was able to shift the clouds into rain and cover the sky with one hand.
He could overrun the entire world and go anywhere as he pleased.
He pacified wars and held the world in awe.
He was matchless in the world.
However, his hair turned white overnight for his beloved woman and he was on the verge of death.
He was surrounded by enemies who were trying to take his life.
He struggled his way to become mighty and fought for everything he cherished.
For this age, he was the only king of the Dark World.
His name was a byword for might.
As a man living in the world, his only ideal was to pursue brilliance.

At 79, Adom is an old mage who has known nothing but illness and regret. When the world finally burns and all hope turns to ash, at the last beat of his fading heart, a mysterious being appears in the dimming light with a simple question:“If you could try again, would you?”What's left to lose when you've already lost everything?A handshake seals the deal, and Adom wakes up on his old school grounds, sixty-seven years in the past. When everything is still possible. A second chance with all his knowledge intact, his memories preserved, and his youth restored.This time, Adom wants it all: to feast on food he's never had, to travel a world still full of wonder, to finally live the life he dreamed of. There's just, as always, one small catch—he needs to prevent the end of the world first.But as Adom will soon discover, changing history might demand sacrifices even greater than watching it burn...

An extraterrestrial thing gives Chen Yizhe the ability to transform the microscopic world

Repair electronics?

To cure all diseases?

Modify DNA information?

Change the structure of water into gold?

Create new material?

- Description from novelbuddy

Why is it “Hero” that “Savior” that? Why is it always the same happy ending? “Happy” “Good” “Perfect” endings? You know what? SCREW IT. I will give you all the worst possible ending possible? Why? Because I’m an asshole!