Available as both manhwa and novel.
The Apocalypse-Level Death Knight Returns El Regreso del Caballero de la Muerte Clase: Apocalipsis
Also known as: El Regreso del Caballero de la Muerte Clase: Apocalipsis · El Regreso del Caballero de la Muerte Clase: Apocalipsis Novela · Myeolmanggeup Death Knight-ga Hoegwiham · 멸망급 데스나이트가 회귀함 · Return of the Apocalypse-Class Death Knight · Return of the Calamity-Class Death Knight · The Apocalypse Death Knight Returns · Tử kỵ sĩ diệt thế hồi quy · 灭亡级死亡之夜回归 · 絶望級デスナイトが回帰した · The Apocalypse Death Knight Returns (French) · Apocalypse-Class Death Knight Returned · Return of the Cataclysmic Death Knight · Jongmalgeup Desu Naiteuga Gwihanhaseotda
Everyone's talking about how troublemaker Demian Haxen's suddenly become a devoted son and brother. What they don't realize is that he's returned to the past after spending decades as the brainwashed death knight of Dorgo, the archlich who murdered Demian's family. Given a second chance at life, Demian's out to power up and protect his family to defeat Dorgo when he comes to conquer the world. But will Demian alone be enough to prevent the apocalypse? Or will his failure mean death for them all?
