Shinwa Densetsu no Eiyuu no Isekaitan - Volume 9, Chapter 5 – Ice Emperor, Part 2

Aliandra Amariel loved magic, dedicating her academic years to the study of runes and spells, pushing the boundaries of mana's infinite possibilities. Like most Fae, her destiny seemed clear until that fateful day of her Class Trial, when the Blind Lich unleashed an undead apocalypse on her home, the fabled underground city of Dal’mohra, and triggered The Breaking – a cataclysm that forever reshaped the world. Saved by her mother’s legendary time-stasis spell, Ali wakes thousands of years into a dark future. Everything she knew and loved is gone, buried under a mountain, transformed into a twisted dungeon by the malevolent will of the Lich. Now, Ali must confront her deepest fears, mastering the arts of battling monsters and braving a town riddled with corruption. As the Lich's grand design shadows her every move, she scrambles to forge new friendships and unearth ancient knowledge in her fight for survival. Why must she struggle? All she had ever wanted was to curl up in a comfy chair with a few thousand good books. But the immortal Lich is drawn to her unique magic, ever hungry for more power to fuel his cold-hearted ambitions. How will she survive the giant target painted on her back as her advancement slowly reveals the horrifying truth of the Class she chose to save herself? Will she falter, forced into the eternal servitude of undeath, or will she rise against all odds and cast him down, ridding the world of his evil?

A thousand years ago, the Great Calamity struck Earth. Countless rifts tore through reality, opening portals between the Demon Realm and the Human World. Overrun by monsters, humanity was on the brink of extinction. But at its darkest hour, something miraculous happened—those who died returned, awakening strange new powers that allowed them to fight back.Vale knew that story well. Maybe that's why he wasn't surprised when he heard the voice of the system speak to him.[ Congratulations! You have died. ][ Your First Trial of Death begins now. ]What truly shocked him, however, was the question burning in his mind:“Who would dare to assassinate the Second Prince of Verythmia?”

Li Yi accidentally obtained a black science and technology library, which contains countless books of the inheritance of high-tech civilization and records countless knowledge.

There are thousands of bells in the book, there is a golden house in the book, there are many horses in the book, and there are Yan Ruyu in the book.

Li Yi has completely turned into a bookworm, learning all kinds of knowledge from the library, grand unified theory, particle Tebo theory, …, acquiring various black technologies, superconducting materials, super batteries, intelligent algorithms, … .

- Description from novelbuddy

I finally managed to kill the demon lord.