Library of Heaven's Path - Chapter 1422: I Thought Of You As My Brother, But You Flirted With My Younger Sister?

The status of a wizard is transcendent in all continents and in the universal plane.

5 years after the world changed, the final boss appeared.

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

Eli was transmigrated to a world of magic and became immortal.

He had endless life and could never die.

“Huh? I’m talentless? Then, I’ll just train for as long as I need, even if it takes 1000 years. That should be enough for me to become strong.”

“The skill is hard to learn? Then, I’ll take a few dozens of years to research it. There’s no way it’s that hard, right?”

“What? I can sacrifice my life force to gain spirit power? That’s a bargain!”

“The enemy is here? Hell, I’ll just hide for 10000 years. Let’s see if he can outlive me. I’ll come out once he’s dead.”

This is the story of an immortal who first struggled to live in the world of magic until he became strong enough to slaughter endless worlds.