Kikansha no Mahou wa Tokubetsu desu

The world is on the brink of destruction after a devastating ten-year war in the "shadow labyrinth." Desir Arman is one of the last skilled magicians left standing, but even he is no match for the formidable foe threatening humanity's very existence. Just when he's certain the end has come, he is sent back in time to his early days of studying magic at the prestigious Hebrion Academy! With this rare second chance, Desir is determined to save not only himself but also the friends and comrades he once lost. Armed with the knowledge of what their future holds, can his efforts make a difference, or are they all doomed to relive the same terrible destiny?

(Source: Tappytoon)