Martial King's Retired Life - Chapter 23Book 15:

Three years ago, Yun Qing Yan fell into the Immortal Realm from the mortal realm. Three thousand years later, he became Divine Emperor Yun who shook the entire Immoral Realm. Breaking through the void and returning back to the mortal realm, Yun Qing Yan discovered that only three years’ time had passed here. “In the past, I did not possess the power to protect the people I hold dear. Now, I want the entire world to grovel at my feet.”

- Description from Novelupdates

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!

With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

Following the death of the emperor, the Astanian Empire plunged into chaos. His two sons both aiming for the throne caused a civil war that divided the empire.In the midst of this conflict, Alaric was forced into conscription. He later joined the crown prince’s army as a company commander.He led his 100-man army into battle, fiercely fighting with the hope of a better future. Unfortunately, he was just too weak to cause a ripple on the battlefield.A single arrow to the head shattered his hopes and he died without even a proper burial.Just when he thought that everything was over, he found himself back to his younger self with his memories intact.Armed with his knowledge of the future and a system that awakened his dormant powers, Alaric began his journey to overcome his fated demise.

Calamity descends upon a a tranquil world in the black of night, transforming it into a death game! This a a true apocalypse, but this is not the end of humanity!

- Description from Novelupdates