MTL - Everlasting Sword God - Chapter 42 Three years

The protagonist, a famous YouTuber known for playing the game trilogy “Tril Trilo Trilogy,” finds himself possessing the final boss of the game world.Before the release of the new instalment in the series, he receives an offer from the game’s developer to play a prequel, “Part 0,” which explores events that occurred before the first instalment. Since he is a fan of “Tril Trilo Trilogy,” he eagerly accepts the offer.However, through some twist of fate, he wake ups in the world of “Tril Trilo” in the dreadful body of the final boss of the trilogy, a character named Frank Wonderstein.

Viserys Targaryen was born with the blood of dragons and yet lived his life in exile. He was a prince with a lost kingdom and a fading legacy, an immature bastard who died a pitiful death. Unfortunately, that same death was coming for me now… as I found myself in his body right before molten gold fried my brain.Yes. Fuck Khal Drogo, and fuck the molten crown.With the memories from another life, in this world of betrayal and broken oaths, I had the chance to forge a new destiny for myself. Armed with the knowledge of the future, my own cunning, and [The Dragon System], I made the choice to flee from the Dothraki barbarians and take back what was rightfully mine.

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