Heavenly Demon King

We are on Netherworld Island, which is isolated from the rest of the world. I think it would be impossible to poison my master to death, right? I grew up rough-skinned and thick-skinned, and was treated like a human punching bag by the village bullies. Pay him back after the fight, well, he is a good man, I will definitely repay him well in the future! I had a blind sister who was snatched away by an old man on the grounds that "she would eat me." I didn't believe it, so I got a beating. In order to save my sister, I killed demons and climbed the cliff all the way, but the old man told me: "I gave your sister away. You come back to the sect with me to learn the craft and become a poison king." I couldn't beat him, and I couldn't scold him (if I scolded, I would be beaten even worse), so I could only get on the pirate ship with tears in my eyes and worship him as my teacher. My master is an old man who likes to torment me to death and watch me break my defenses. His catchphrase is - "Look, he's in a hurry." My daily life now: I appear to be well-behaved and eager to learn, while I crazily recite "The Encyclopedia of Poisons" while internally thinking about how to poison my master to death. Current progress: 99 kinds of poisons have been mastered, and there are still 999 steps left before poisoning the master.