[Harry Potter fan, single female protagonist, not time travel, no system!
Zhao Yingzhi is a Taoist practitioner from the Xia Kingdom. He was possessed by the soul of a black dragon due to a dragon walking accident. In order to solve his physical problems, Zhao Yingzhi accepted the invitation to study at Hogwarts. During the study abroad process, he and his companions foiled Voldemort's conspiracy, cured Lupine, and finally defeated Voldemort.
But defeating Voldemort is not the end. There is actually a big BOSS hidden behind Voldemort-Salazar Slytherin. In order to realize his dream, Slytherin activated the ultimate magic - meteor shower. Thousands of asteroids were pulled by Slytherin's magic and fell towards the earth. In order to save the earth and save his friends, Zhao Yingzhi was forced to take risks and finally became an immortal. Only then did he prevent the catastrophe and eliminate Slytherin.
