By the Fates

1. Meet and Talk to the handmaiden at the villa

2. Follow the handmaiden

3. Kill the Order Guard ambush 0/3

4. Interrogate the handmaiden

5. Reach the altar and Deal with Diona

Diona and Eritha are twins. Diona is on the right.

6. Kill Diona

6.1. Talk to the high priestess

7. Kill Diona (Wrong One)

If you killed the wrong sister, you will find out about it by searching her corpse. You will also have to kill the right Diona and her companions.

8. Quest Completed

Rewards: Legendary XP, Legendary Drachmae, Armor of the Immortal (Legendary Torso), Artifact Fragment, Letter to Diona (Cultist Clue)