The Bane of Cairn
The final Act 4 main quest, offered by Ulgrim in the Necropolis Interior after The Necropolis. Destroy three Blood Wagons, enter the Tomb of the Watchers, defeat Loghorrean, the Voice of Ch'thon, and report to Inquisitor Creed at Fort Ikon. Completing it unlocks the next difficulty in the base game.
The quest giver is Ulgrim beside the Necropolis Interior Rift, not Creed. The seal blocking the Tomb of the Watchers weakens only after all three Blood Wagons—north, east, and west—are destroyed in the same session. If you leave the session before finishing, the wagons can respawn and must be destroyed again.
- 1Accept the quest from Ulgrim
- ▸Complete the preceding main quest, The Necropolis.
- ▸Speak to Ulgrim beside the Necropolis Interior Rift and accept The Bane of Cairn.
- 2Destroy the three Blood Wagons
- ▸Find the northern, eastern, and western Blood Wagons placed around the Necropolis Interior for the current session.
- ▸Attack and destroy each wagon, then confirm all three objectives are checked in the quest log.
- ▸Because the wagons can return after leaving the session, destroy all three and enter the tomb without returning to the main menu.
- 3Descend through the Tomb of the Watchers
- ▸Pass the weakened cultist seal and enter the Tomb of the Watchers after destroying all three wagons.
- ▸Descend to the Seal of the Loghorrean and meet Ulgrim at the bottom level.
- ▸Defeat Bloodlord Thalonis to open the entrance to the Edge of Madness.
- 4Defeat Loghorrean and report to Creed
- ▸Defeat the final boss, Loghorrean, the Voice of Ch'thon, in the Edge of Madness.
- ▸Return to Fort Ikon and report to Inquisitor Creed.
- ▸Rewards are 25,000 / 55,000 / 102,000 XP by difficulty, +1,000 Black Legion reputation, and a random Legendary item. With Ashes of Malmouth installed, the Act 5 route continues afterward.
If the quest is not offered, check for Ulgrim beside the Necropolis Interior Rift. If the tomb entrance is sealed, verify that the northern, eastern, and western Blood Wagons are all destroyed. If the seal returned after you had destroyed them, destroy all three again in the same session.