Long before Sanctuary faced the Prime Evils again, Archbishop Lazarus played a crucial role in unleashing Diablo beneath the Cathedral of Tristram.
The original Diablo sent you into the Unholy Altar to hunt the corrupted Archbishop after discovering his betrayal and involvement in Prince Albrecht’s disappearance.
Season 15 recreates that memorable quest as a Waking Nightmare, complete with the Books of Vileness and another confrontation with Lazarus.
Unholy Altar Location
The Unholy Altar Waking Nightmare is located in Chambatar Ridge within the Dry Steppes, with its entrance permanently marked on the world map.
This places the recreated dungeon far from Tristram, where the original Unholy Altar was encountered during the final stages of Diablo.
Unholy Altar Walkthrough
Enter the Unholy Altar and begin exploring while fighting through the enemies blocking your path and searching the dungeon for the Books of Vileness.
Continue through the different areas and interact with the required books until the objective is complete, allowing you to proceed toward the final encounter.
Head through the portal leading to Archbishop Lazarus, then defeat him and the enemies surrounding him to cleanse the Waking Nightmare and complete the dungeon.
How To Find The Books of Vileness?
Explore the Unholy Altar while clearing enemies and revealing more of the map until you eventually locate each of the required Books of Vileness.
Finding these books mirrors the original Diablo quest, where two Books of Vileness had to be activated while progressing toward the confrontation with Lazarus.
Keep checking unexplored sections until the objective is finished, after which you can follow the dungeon objective toward the portal leading to the Archbishop.
How To Defeat Archbishop Lazarus?
Archbishop Lazarus waits beyond the portal at the end of the Unholy Altar, serving as the final encounter before the Waking Nightmare can be cleansed.
Deal with the enemies accompanying him while keeping pressure on Lazarus, using your defensive abilities whenever the surrounding monsters begin overwhelming the arena.
Once Archbishop Lazarus has been defeated, the encounter ends and the Unholy Altar Waking Nightmare will be successfully completed.
Unholy Altar Rewards
Completing the Unholy Altar provides loot from Archbishop Lazarus and the enemies encountered while progressing through the dungeon toward the final confrontation.
Clearing the Waking Nightmare also contributes toward seasonal progression and provides another opportunity to earn Prime Evil reputation for your currently equipped Splinter.
There are no unique rewards exclusive to the Unholy Altar, making its seasonal progression and regular Waking Nightmare rewards the main reasons to complete it.
How To Complete Unholy Altar Quickly?
Movement Speed helps considerably when clearing the Unholy Altar, allowing you to move through unexplored sections faster while searching for the Books of Vileness.
Focus on eliminating enemies directly in your path rather than clearing every room, since finding and interacting with the required books should be your main priority.
Once the books are finished, the rest is straightforward: enter the portal leading to Archbishop Lazarus, defeat him, and the Waking Nightmare will be complete.
Verdict
The Unholy Altar represents one of the darker moments from the original Diablo, revealing just how deeply Lazarus had fallen before the final confrontation with the Lord of Terror.
Bringing back the Books of Vileness and Lazarus himself makes this Waking Nightmare feel like a genuine recreation rather than simply borrowing another classic location.
Returning to hunt the traitorous Archbishop decades later is a fitting reminder of how his actions helped set the entire Diablo saga into motion.
