Tips for Toxic / Poison Skill
For poison, do not raise it!
Always start at 0 and leave it at that. You can raise with Miao CaiDie (the girl from Jiuli Tribe) for free. She will raise your poison stat +5 per day until you reach 100.
Once you’ve reached 100, she will stop doing this. The reason is that for every +5 poison, you can save scum and get a random attribute of STR, CON, DEX, etc.
So if you start off with 0, she can do it 20 times, giving you free 20 attribute points. The downside is that it also comes with -25 HP.