Assassinate the Time Traveler

He traveled through time and became the abandoned son of a big family. He showed his talent for magic at the age of four. He entered the magic academy at the age of five. He graduated at the age of eight. He invented gunpowder at the age of ten. At the age of eighteen, he became a general and led an army to sweep through the enemy country... It's such an exciting story about time travel and hegemony, but... Chang An is not the protagonist of this story. As a time traveler killer, Chang An's mission is to assassinate this time traveler before he causes greater damage to the balance of the world!