Poison-Eating Healer 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

Cheon Haesun is the protagonist who‘s terminally ill because of various poisons. Cheon Haesun, who was never welcome anywhere, will have his story of becoming the strongest hunter play out on an Earth upon which dungeons and monsters have broken out!