I Became a Student at the Transcension Academy - Chapter 3

As 21 years old Noah closes his eyes for what he thinks will be eternity, he wakes up in the body of a girl 7 years younger than him.Vasilisa, as she is known, is hated and mistreated by the people around her because of the Muddy Tongue curse which not only impedes her speech, but makes her magic unstable.This effectively makes her the harder than hard mode when it comes to reincarnation, and, of course, fate made her his “avatar” in this new world full of mechanics he only ever saw in video games.Despite this, Noah as decided…Whether as Vasilisa or himself, this time he will find a way to exist for the world.

After dying from betrayal, Thomas reincarnates as Jolthar Kaelzhar, the neglected son of a powerful clan, just after his brothers kill him. With Jolthar's memories and the blessing of Qalena, Thomas vows to rise from his lowly position and claim power in his new life.

Luo Zheng is at the bottom of the Luo Clan hierarchy, despite his family being the founders of a power refining technique that could instantly defeat any opponent.

One night, enraged by unfair treatment from a family steward, Luo Zheng burns the family records. In doing so, the hidden magic in the book engulfs him and Luo Zheng becomes a new skilled fighter. Fleeing his home and despicable clan, Luo Zheng must learn to harness his powers to rescue his younger sister while his own cousins are on his pursuit.

- Description from Novelupdates

As a successful villainous BOSS, in addition to having ideas and aspirations, one must also keep in mind three points:First, grow sneakily, don't act rashly (once a villain acts rashly, they basically won't survive past three chapters).Second, you're not a good person, so be ruthless (becoming more evil will make you three times stronger, while redemption weakens you by seven times).Third, remember the two points above. The moment you forget them, your end is probably on its way.