Absolute 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

The tower. An unknown place with many rapid changes. Ten years later, I reincarnated into the body of a boy who lives on Earth in South Korea. “The guy who backstabbed me and the one above him… I’m going to rip into them. ” The person who reached the top as a necromancer and achieved the class above that, Spirit Master Cha Jinhyuk. As the “All-Master,” he will take his revenge by climbing the tower as a necromancer (spirit master).