1 - Nasrudin's Shack Inside you'll find Nasrudin, who isn't actually dead. He'll give you more details about why Arronax was sent to the Void, and, when you update him about what's been going on, he'll tell you that the only way he can think of to defeat Arronax now is to use the Vendigroth Device on him. Of course, Nasrudin won't remember where Vendigroth is, but he'll mark the Gateway to the Wastes on your world map. Finally, Nasrudin will tell you that you'll have to face Arronax in the Void itself rather than waiting for him to return, and he'll offer to banish you there if you meet him at the Ring of Brodgar after acquiring the Vendigroth Device.
Note 1: If the conversation with Nasrudin seems slightly off, that's because it skips a piece of pivotal information, that Arronax was banished because he destroyed the technological city of Vendigroth. That's why the city was preparing the Device to use against him.
Note 2: If you're evil, Nasrudin won't trust you completely, and he'll give you a quest to defeat the Bogaroth, the creature that killed off the Ashlag Tribe. He'll then mark the Lair of Bogaroth on your world map. The Bogaroth is only level 20, so defeating it shouldn't be a problem.
Note 3: If you have Raven and Virgil with you, they'll both speak to Nasrudin.
Note 4: If you attack Nasrudin, he'll send you to the Void.
A. Exit to the Land Bridge.