Invincible Poison God

In the wild world, all kinds of poisons are fighting, but I am the only one who is undefeated! Medical doctor Gu Qing died of poisoning on earth, and his soul traveled to a world filled with only poison. I studied medicine in my previous life and practiced poisoning in this life. A doctor needs a benevolent heart to save the world; a poisoner needs a ruthless heart to kill. You are ruthless, I am ruthless than you, this is the way to remain invincible!