MTL - Marvel: I Am the Man of Steel! - Chapter 135

Vincent Strider was a gun for hire who made a living by killing whoever it was his clients wanted dead. But during one mission, he died in a fierce gunfight. However, death was not the end for him. Vincent found himself reincarnated in another world, facing a floating interface that flickered before his eyes.[Synchronizing Host!][Military System initializing.]Vincent found out that in this system he received, he can summon soldiers, tanks, aircrafts, and even warships! This is going to be exhilarating.

“How do you treat ants? Gods will treat you the same!” – Yuan Chenfei.

On this day, Gods finally appeared.
Not for destruction, not for slavery, but just for playing a game…

- Description from Novelupdates

Lucian Bowcott only wanted a quiet life. He met up with old friends, made a wish, and died after one drink.Now, he awakens inside a coffin—summoned by the Half-Dead Queen of Atraeum and surrounded by restless souls.Armed with the Death Grimoire, Lucian must embalm corpses, repair brittle bones, and help the dead find peace… before something ancient finds him.As his powers grow, so do the whispers in the dark. If he wants to survive, Lucian must unravel the Queen’s grief, discover why a mortician hasn’t been summoned in over a century, and confront the entities haunting his every step.A/N: It doesn't deal with dungeons, Lucian's system is a magical book, and he slowly unlocks powers to help him with his next assignment. He travels to different places around Atraeum, and in the future, another kingdom.This is a character-driven gothic isekai about an introvert learning that sometimes, peace is more than just embalming a body and preparing it for a funeral. He's more of an undead therapist now

How can there be any invincibility?

How can there be any Xeon undefeated?

No one in this world can be eternally number one, anyone can be defeated.

including me.

I’ve been waiting for that one person to show up, beat me, tell me that my way is wrong.

It’s a pity that that person hasn’t come yet.

…

False martial arts: strengthen yourself, break the limits of the human body, and resist bullets with flesh and blood.

Real martial arts: use the magnetic field of life to dominate the magnetic field of the stars, use the small universe of the human body to attract the power of the big universe, travel the starry sky, and smash the planet.

- Description from novelbuddy