MTL - Martial Peak - Chapter 5971 Guards, reinforcements

Bai Aoxue, the best mercenary in the 21st century, is accidentally sent back to the Chengxi Dynasty in Great Continent due to an explosion in her mission, and trapped in the first daughter of Prime Minister. After her rebirth, she is set up by her father to marry the 5th prince Jun Yeyan who wears a mask all day long.
In the face of bloodthirsty enemies, discord between brothers, collusion among courtiers and invasion of enemy state, can Bai and Jun resolve the crises? What will happen to their political marriage? How will the fierce battle for the throne end?
With many twists and turns, the book brings you to experience palace revolution, love and hatred thousands of years ago.

- Description from Novelupdates

Born as the thirteenth son of the grand Kingdom of Ironhelm, Prince Liam is far from being considered a contender in the race for the throne. With his father, King Elijah Orlean, having only eight years left to choose the next heir, Liam’s prospects are slim. Seen as the boy with the least mana talent, he is overlooked by the court, his siblings, and even his tutors.But appearances can be deceiving. At just thirteen years old, Liam is secretly an Expert Mage, capable of wielding magic with precision and power that even the most talented in the kingdom would envy. Determined to keep his abilities hidden, Liam embarks on a path of quiet preparation, honing his skills in secret while navigating the dangerous political intrigue of Ironhelm.

Transmigrating into a fantasy world, starting as a typical rich and handsome guy, he has a useless main character fiancé, a sister who knows the future plot, and a distant cousin who is the reincarnation of his nemesis, the Nine Heavens Mysterious Maiden.He becomes the final boss in a female-oriented novel, forcibly killed by the plot?Although he has a system that allows him to become stronger by binding with geniuses, Jiang Minghan states that as a gentleman who likes to stay calm and friendly, he just wants to be good to others and doesn’t want to be a villain.To avoid the fate of being overpowered by the female leads in the future, he can only walk further down the path of a villain.But unknowingly, when did he become the source of darkness, disrupting the eternal heavens?