Vendigroth Ruins
- Cross the Wastes to the ruins Pelojian marked on your map. Enter the building to enter the Ruins of Vendigroth.
- In the northwest corner of the first area you will find the first key. Use to open the locked door nearby and click on the vent to proceed to the next area.
- Go right in the next area to find the second key at the end of the road. Near the center of the area you will find the locked door behind which is the vent to the next area.
- The third Vendigroth Key is found in one of the three drawers in a room in the northeast corner of the third area. Enter the vent at the south end of the area.
- Continue through the next vent and you will find yourself in a building filled with automatons. Take the fourth key from a chest in a room to the south.
- Open the locked door on the east side of the building and descend into the basement.
- Defeat the automatons in the large room in the basement and take the Vendigroth Device from the chest at the back of the room. Once you have the device, leave the Vendigroth ruins.
The Void
- Travel to Roseborough north of Caladon and go to the Ring of Brodgar northwest of town. Nasrudin will be there. Speak to him and he will send you into the Void.
- Step on the platform to the right to move to the next area. Take the stairs down into Arronax's Lair.
- The guards will allow you to pass so that you can speak to Arronax. You will find him trapped in a shell which he claims Kerghan locked him in after defeating him. He will show regret over his previous actions and will claim innocence about the latest happenings in Arcanum. He believes that Kerghan has been impersinating him. Release him by killing the three monsters in the hallway and he will offer you join you to help you defeat Kerghan.
- Step on the circle in the room behind Arronax to continue to the next area.
- Cross the bridge and enter Kerghan's stronghold.
- Step in the circle at the east end of the first floor to proceed to the second. Here you will find the device that was supposed to create a gate for Kerghan to return to Arcanum.
- On the third floor you will find the remnant of the Black Mountain Clan. One of the dwarves will tell you about what they are doing there and how Stennar was able to escape. Step on the circle near the center of the floor to go to Kerghan's Inner Sanctum.
- Kerghan will tell you his side of the story and why he wants to return to Arcanum. You can choose to either help him, or defy him.
- If you choose to help him, he will ask you to kill the other four in the Void: Arronax, Gorgoth, Kraka-Tur, and the Bane of Kree. Once you have done so, return to Kerghan and together you will exterminate all life on Arcanum.
- If you choose to defy him, he will change into his true form and attack you. Once you have brought his HPs to 0, he will retreat into a healing shell. Use the Vendigroth device on him to destroy him for good.
- After you have destroyed Kerghan, you will return to Arcanum through the breach the dwarves had created. You will see several cinemas showing what happens across Arcanum after your victory. What happens depends on the side-quests you completed during the game.