Seoul Station’s Necromancer is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

[You have entered the dungeon at Gwachun Station’s 1st Exit.]

“What is this?”

A necromancer had returned to earth after 20 years, and the subway station… No, it had become a dungeon.

Bow down to the majesty of this one man army as I begin to seize the world.