The Marshal's Wife is Wild - Chapter 135 - 134 League Match 20, Concerned

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

Greed, envy, anger, gluttony, lust, sloth, prideThe 'Black Book' records seven sources of sin, which are also seven steps to ascend to godhoodOnce, I thought there would always be one sin suitable for meBut I never expectedEvery volume of the twelve military letters bears my name!

Ethan Carter was a failed fantasy author who died overworked and bitter. When he wakes up in the world of his own unfinished novel, he finds himself reborn as Darius Wycliffe, a weak and arrogant noble fated to be killed by the protagonist, Lucien Ashford, the Archmage’s Disciple.But Ethan refuses to die so easily. Armed with his knowledge of the world’s secrets and a unique ability to rewrite spells, he dives into the forbidden magic he once created but never fully explored. As he grows stronger, he uncovers terrifying truths about the world he thought he knew.To survive, Ethan must defy destiny, master the deadliest of magics, and challenge the very hero he once wrote to be unbeatable. But what happens when the lines between hero and villain start to blur?