The Cursed Prince's Strange Bride - Chapter 37 Mysterious Princess Amber.

I was a genius in the Earthen Plane.

“With my knowledge, give me a fulcrum on which to place it and I shall move the world!”

…

Sorcerer Continent—a world where sorcerers exist. Wielders of arcane knowledge. Masters of all elements. Sovereigns of space and time. These sorcerers governed the world with their unrivalled prowess. One day, a young man awakened into this world with his past forgotten and no place to call home. Follow along as Glenn, by relying on his luck and wit, tries to survive and advance in this unforgiving world. Entangled within the machinations of fate, political schemes, power struggles and wars, he forges his own path and creates a place for himself.

- Description from Novelupdates

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.

Yin BiYue has made the worst purchase ever. After transmigrating countless times into the bodies of canon fodder villains, he buys a ‘Fiend Halo’ from the Rebirth Company, supposedly the best aid for an up and coming final BOSS!