Walkthrough

1. Accept the quest from your trainer in Job Center and get a Training Badge.

2. There is something wrong with Du San. Talk to him, and seek for General Judd. Judd knows that Du San was bitten by the snake men. You are asked to avenge him. The snake men are hanging around in the west of Ape City. Kill them till you have a Venomous Fang in your inventory.

3. Take the Venomous Fang to Pharmacist Dong. He extracts the Red Toxin, Green Toxin and Blue Toxin from it. You need to combine two of them together. Only by combining the right pair in the right order can teleport you to Kun Lun.
There are some effects about the combination:
Blue Toxin and Green Toxin: You will be teleported to Kun Lun.
Blue Toxin and Red Toxin: You will get poisoned.
Red Toxin and Blue Toxin: You are recovered.
Red Toxin and Green Toxin: You become strong.
Green Toxin and Blue Toxin: You are floating.
Green Toxin and Red Toxin: You are turned into a zombie.

4. Collect 7 powders from the 7 stones in Kun Lun by right clicking them. Then right click one of the 7 powders to combine them into a pile of Rainbow Powder.

5. Bring the powder to Du San. He will get well at once and reward you an Ultra Badge which you can swap it for a reward from your trainer (the one who can promote you) in Job Center.