At the start of Chapter 3, go to the Purple Wyrm inn and talk to Randalla abut a new mission. This will be the misson that is set personally for Dorn. She will tell you that you need to meet with a Druid and help her with a problem. After you defeat him, take the key from him. It will open a room that has 500 gold and three chests. After that, talk to the Druid again. You will get your reward of gold and experience, as well as new abilities for Dorn.