Magic System in a Parallel World - Chapter 14: Mana Fatigue

Zavier met Cosmic Consciousness after his death. He was satisfied with every system that Cosmic Consciousness exhibited, so he wanted all of them. Surprisingly, the Cosmic Consciousness obliged him.

Zavier was reborn in an isekai full of magic and alchemy. Now, he had many routes to upgrade. Interestingly, to coordinate these systems, Cosmic Consciousness gave him the gift of being able to duplicate himself. He could clone a finite number of himself to manipulate these systems.

Magus, Alchemist, Mesmer, Tamer, Hunter, Vampire, Werewolf, Dragonknight, Necromancer.....

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By the way, it wouldn't appear NTR or some bullshit harem of courtships. MC of course will have harem but not for cliches.

In her past life, Shen Xi always longed for love and validation from her parents, members of the wealthy Su family. Unfortunately, the attention that she yearned for was stolen by the family’s fake heiress – her elder sister, Su Ruowan.

In the year 3021 of the Western calendar, the last world war broke out and the earth was destroyed.
A group of survivors left their homes to settle on new planets. New races, new classes are born. Cities began to be built, countries rose one after another, conflicts between different races intensified, and social order was re-established…
The transformation from a survivor to an aggressor was but a moment.
This is a world where the strong are respected and the fittest survive.
Shang Ping was reborn from the earth in the 21st century to this planet. The moment he woke up, his fate had already begun to change.

Content Labels: Strong Soul Conversion Court Marquis Heaven’s Chosen
Search keywords: Protagonist: Shang Ping ┃ Supporting roles: Solan Edrich, Liu Xi, Austin ┃ Others: future time and space, battleship, interstellar war, rebirth, distant starry sky

- Description from novelbuddy

He was the cold-blooded prince of the Jin country. Decisive and smart, he had looked down on the world with apathy and disdain.

She was his Wang fei, a person who had saved him in the past, but even he wouldn’t look at her.

When the fire raged and death claimed her, it was only then that she realized her existence was nothing but a joke from the beginning.

She opened her eyes once more after spending two years as a roaming, vengeful ghost. In this lifetime, Ye Zhen promises that she will be a different person. With a slight smile, she will ruthlessly trample on those who had schemed against her and lied until her demise!

Most importantly, she would let him experience the pain of an unrequited love; the bitterness of seeking something you cannot obtain!

- Description from Novelupdates