- Talk to Lod in Falkreath and he’ll ask you to find a dog he’s admired
- Track down the dog just west of town
- Travel with Barbas, the dog, to the shrine of Clavicus Vile
- Retrieve The Rueful Axe in Rimerock Burrow
- Return to the shrine of Clavicus Vile
- Give the Rueful Axe to Clavicus Vile OR kill Barbas with the Rueful Axe
- To obtain the Masque of Clavicus, insist that Clavicus Vile take back Barbas and the The Rueful Axe.
In order to start this quest, you will need to travel to Falkreath and speak to Lod who is the town’s blacksmith and will be at his forge between 8am and 8pm like any other blacksmith. Upon talking to Lod, he will ask you if you have encountered a dog on the road and after telling him you didn’t see a dog on the way in, he will ask you to search for the dog. Accept the task and receive a piece of meat, then after making your way to the quest target, Barbas the dog will approach you and immediately talk to you, saying you are “exactly what he has been looking for.” Agreeing to help out Barbas, you can either follow him or make your own way to Haemar’s Shame where you will now have to fight your way through a group of Vampires which includes assisting Barbas just in front of the Clavicus Vile shrine.
Once you have killed the vampires then you will speak to Clavicus Vile and he will tell you about an “incredibly powerful axe” known as the The Rueful Axe and will ask you to retrieve the axe for him in order to receive his boon which is the Masque of Clavicus Vile. The Rueful Axe is located at Rimerock Burrow which only has a Flame Atronach and a powerful mage called Sebastian Lort inside who can provide a challenge if you are not careful of his shock spells. Just behind Sebastian is The Rueful Axe. Once you have the axe, return to the shrine of Clavicus Vile.
Now once you return with the axe, you are given the option to keep the axe in exchange for killing Barbas with the axe or simply tell Clavicus Vile to keep his axe and take back his faithful companion in order to get the Masque of Clavicus Vile. If you choose this over keeping the axe then Barbas will be transported back to Clavicus Vile’s side on the shrine and Clavicus Vile will be restored to his full power once again. He implies he’s going to go out and explore the world again but you never hear from the Daedric Prince after this quest.