2-Shuume no Daimadoushi wa Kinsetsu Mahou de Musou Suru

When Vidrak the Death God invades and the fate of humanity hangs in the balance, the greatest mages of the realm stand in defiance… only to find that their spells have no effect, as the dark overlord effortlessly picks apart their attacks. Overwhelmed by a horde of monsters, long-range mage Setsuna Cromwell uses his last resort, the Amulet of Resurgence, to travel 10 years into the past. Now a freshman twice over, Setsuna must go against the grain by studying melee magic, known as the least prestigious domain – and the only one with a chance of defeating Vidrak. (Source: WEBTOON)