MTL - Meeting A Demonic Cultivator, Even God Cries - Chapter 6 who are you?

After transmigrating into the Marvel-DC multiverse, he, once an ordinary person, has now become a world-renowned mercenary and assassin.Things have changed. Should he become a righteous hero, or continue his dark profession?“Don't use such shallow concepts like good and evil to judge me. I only do what I want.”Suddenly, the protagonist appeared behind the author of this synopsis, punched him, and sent him flying.“The truth is simple. I am the death knell that rings in everyone's ears!”

Mortimer Zhu is an extremely unfortunate high school student who accidentally enrolls into an academy of a dubious nature, where it is the norm to jump in front of moving trains, get dismembered during orientation, and crushed by vindictive bouncing classrooms. Can he stay alive or will he die from the rigors of school? Why have evil spirits suddenly acquired a taste for his flesh?

- Description from Novelupdates

[You have entered the dungeon at Gwachun Station’s 1st Exit.] When former high school student Kang Woojin finds himself returned back to Earth after being forcibly summoned to a foreign planet for 20 years, he soon finds that Earth is not the same, normal place as he once remembered it to be.

The aliens came with hostility.
Facing the invasion of aliens, human beings are weak like ants.
So this is the end, the real end.
But there is resistance when there is an invasion.
For some, this is not the end, it is war.
So this is war.
Real war!

- Description from Qidian