Hell's executioner

Hell has always been a haven of unlawfulness but that doesn't mean that there are any rules. One thing is that if they want an Overlord can order someone's execution and everyone else have to naturally agree to it and the royal family has the final say in it. When given the go ahead they call upon the executioner who is a sinner demon who specializes in crafting various poisons with different effects depending on the poison itself but one thing remains consistent and that's the pain and tourcher of the victim before they eventually die.