To the West of the Lighthaven bridge (in its extension), you can find a yellow goblin named Dorken the Putrid.
Kill him, and one of the following 3 people will be sick with the goblin fever.
Speak to Geena, who is at the Lighthaven tavern. If she is sick, go to Windhowl and speak to the farmer in his field; he will give you a remedy. Bring it to the Lighthaven tavern owner who will thank you.
Speak to Kalastor, and if he is sick, go to Windhowl and speak to the Sniffer, who is located to the north and teaches dodge. He will sell you a Purity Elixir for 800 gold. Bring it back to Kalastor.
Speak to Murmuntag, and if he is sick, you will need yellow powder to cure him, which drops from Araf Kul or Roshnak Tul.
The appearance of Dorken the Putrid is rare, but it can be worth it!
Reward, depending on the person cured: