In fact, Yeon-woo acquired something slightly different from Poison Blood.

[Disabling Poison Blood]
[Number 28]
[Description: A combination of the poison of souls from the 30th floor, Anti-Venom Bayluk’s poisons, Devil King Poison, and a few Draconic Factors. It can cause critical damage depending on how it is used. Your blood will also become acidic and poisonous.]
[*Hundred Poison Immunity
You gain a strong resistance to many poisons and acids. Even if you are poisoned, immunity will be created quickly. You will automatically store the information about the poison. ]
[*Poison Factory
An organ that exudes poisons will be created next to your heart, allowing the poisons to flow through your circulatory system. The information from the Hundred Poison Immunity will influence the quality of the poisons. If the concentration of poison in your blood exceeds a certain threshold, you may be harmed. The higher the skill proficiency, the more superior the poison is.] 
[*Poison Fog
A large amount of your blood will be used to create heavy Poison Fog. The closer you are to the center of the Poison Fog, the stronger the poison becomes and the more symptoms you will deve...