Oblivion Portals are portals to the Atoll of Immolation public dungeon which appear at random around Blackwood and the Deadlands. Upon entering a portal, you must fight your way between islands to reach the Havocrel's Tower in the centre of the map. There you must defeat the Havocrel Duke of Storms to be able to shut down the machinery and return to Tamriel.
Unlike other World Events, there is nothing on the map to indicate where or when an Oblivion Portal has opened; you must come across an open portal in the wilderness of Blackwood in order to take part. However, their vertical pillar of orange light can help identify them from a distance. When a portal spawns, Dremora will emerge but they do not need to be fought to enter the portal.
For more information on what you might encounter within the portal, please see the main article.
After defeating the Havocrel Duke of Storms and deactivating his Antecedent Cataclyst machine in the Atoll of Immolation, a final loot chest will appear. The loot it contains will depend on whether you entered the Oblivion Portal from Blackwood or the Deadlands. The chest has a chance to contain the following items:
- Unlike other World Events, the final boss will eventually respawn in the main room.
- World Events — A list of other large-scale zone activities