The Lone Necromancer is a Manga/Manhwa/Manhua in (English/Raw) language, Action series, english chapters have been translated and you can read them here.
The Summary is
The world is ending. Monsters from legends appear everywhere. They eat people, conquer the streets, and begin to make dungeons in the buildings and subways. If you could choose one job in this decrepit world, what would you choose? For a “necromancer” extinction is my playground and death my wealth.