- After speaking to Brother Resmus as per the 'Destroy the Demon' quest, you must travel to the Monastery of Vastares at the South-West tip of the island.
- Once there, you can speak to Sister Elfwin, at the right-hand door. Elfwin is feeling unwell, and you will have the option to use the incantation you learned from Resmus. This won't cure her, but it will cause the demon possessing her to speak and offer a deal. You have two options:
- Accept the demon's offer. It will ask you to kill Sister Elfwin, to cover up any sign of the possession. It ends with:
- Deny the demon's offer. It will say you can't harm it, but the one person it is worried about is the Holy Man who lives in a cave to the south of the monastery.
- Head to his cave and speak to the man, using the dialogue option 'Help Me'. He will sell you a Demon Potion for 50 gold (if you have a high persuade skill he will give it for free). Giving the potion to Sister Elfwin will weaken Abaddon's hold on her, forcing him to manifest and fight you directly. Once he is defeated, speak to Elfwin once more to get the Demon Ring.
- Deliver ring to Brother Resmus. It ends with:
- The Exorcise the Demon Quest has been solved.
- You have lost an item of Demon Ring.
- You have received an item of Brother Resmus' Letter.
- You have received an item of Priest blade.
- Your fame has increased.
After you complete this quest return to Sister Elfwin to gain additional reward:
- Scroll of Enchant
- 'Advanced Magic Shelter' book (+8 Protection Magic)