A lone necromancer who leads an army of immortals, changed his job to become an SSS rank adventurer 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

A lone necromancer who leads an army of immortals changed his job to become an SSS rank adventurer manga, A necromancer rogue who uses necromancy to lead an army of immortals. Rogue, who possesses too much power, has a certain ambition…!? A new adventure of the strongest necromancer begins!