For the Glory of Rome: Chronicles of an Isekai'd Legion - Chapter 23B3 : One Last Charge

She transmigrated into an orphan, thinking that she still had her boyfriend with her, yet in an instant, her world crashed. For the position of heir, he said, “Yao’er, why don’t you become my second wife?” A sentence destroyed her wishful thinking, causing her to end their relationship of two lives cruelly. Leaving the hustle bustle, she then lived in a forest, wanting to find an honest man to spend the rest of her life with. But not long after getting married, she realized that the honest man she married was a bit dishonest.

“Are you not an ordinary hunter?” she stared at the man pretending to be innocent in a furious manner. Is the ending going to be this way? Of course not, the story had just begun from the moment she changed her future.

- Description from Novelupdates

The black dragon that rose from the depths of the South Sea unleashed an apocalyptic tsunami... Flame demons destroyed city after city made of steel and concrete, calmly departing from the center of nuclear explosions... Alien gods attempted to rule the entire galaxy...This is a future world where human technology is highly advanced.It is also an era that sparked a frenzy of Life Evolution in the Martial Path.Li Yuan, a Martial Path student on the verge of taking his college entrance exams, struggled to advance in this world while harboring the peculiar Divine Palace capable of envisioning the galaxy.Years later.“My current flying speed is 122,682 meters per second, and my power burst is...” Li Yuan flew at extreme speeds through the atmosphere about 180 kilometers above the surface of Blue Star, his cold eyes fixed on the massive creature at the dark void's edge, resembling the mythological dragon: “You, must be the strongest among all the invading Demigod life forms.”“It's just unfortunate that I can now be called... Martial God!”

Oscar, a destitute young boy, died in a tragic accident and was reborn in the forgotten realm. As a member of the lowly Birch tribe, his solace comes from the fragments of a guardian's spirit, residing in his soul. After the decimation of his family in the hands of a powerful race known as the dreads, he embarked on the part of revenge, leading him to the path of transcendence.

I finally managed to kill the demon lord.