Monsters Die If They Are Killed is a Manga/Manhwa/Manhua in english language, MONSTERS 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

Su Zhou, who was born with exceptional physical attributes, encountered an evil cult during an oversea expedition with his childhood friend. In an attempt to rescue his childhood friend, he went into the enemy’s base alone. On the brink of death, he made a pact with a great entity and underwent a transcendent awakening in the new era of spiritual resurgence. In this universe that's in the twilight of destruction, one which is filled with monsters, demons, and formidable beings, evil entities are slayed in search of satisfying revenge. He won’t back down in fear, nor will he be bewildered. He doesn’t commit deliberate charity, nor does he seek justice. Su Zhou is the foe of all evils — “I’ll slaughter every evil soul that exists until no one dares to claim its name!” After all, just like that well-known cliche “People die when they are killed”, “Monsters die if they are killed."