How ironic that the only way to cure the rat bites is to collect more poison rat venom and brew an antidote from it! Old man Tang loves rats, and keeps them as pets, so he's constantly getting poisoned by their bites. What we can do is get him the antidote every time!
Rat Fangs
Requirement: Around level 40
NPCs: Old Man Tang (Maple Forest 779,467)
Rewards: A purple bag or a Brass Heavy Ring of Elite or Super Quality.
Note: It's really hard to tell the difference among all the types of rats. The poisonous rats look like Fire Spirits. They have the same size and color.
Walkthrough
1. Pay a visit to Old Man Tang in the southeast village of Maple Forest. He was bitten by his poisonous rats again and he is in urgent need of a Rat Fang to brew an antidote to clear away the poison.
2. Slay poisonous Rats to get the Rat Fangs. They can be found somewhere in the southeast of Maple Forest.
3. Take the Rat Fang to Old Man Tang and he will give you either a Purple Bag or a Brass Heavy Ring as reward.