TL;DR
- Unlocks automatically after completing Between Heaven and Hell
- You enter the Temis Sewers and fight through rats and vengeful spirits
- Progress leads deeper into the Sunken Catacombs beneath Temis
- A Hand of Akarat triggers a ritual and sacrifices himself, spawning the Galvanized Mauler
- Defeat the Galvanized Mauler boss to advance
- Exit to the Plaza Overlook to complete the quest and unlock The Queen and the Saint
- Rewards: 10,013 XP and 480 Gold
Subterranean Secrets picks up the moment Between Heaven and Hell ends. You followed a suspicious Hand of Akarat through the streets of Temis, and now he has gone underground. The sewers beneath the city are not empty — and what you find down there confirms that Akarat’s followers are far more dangerous than they appeared on the surface.
This walkthrough covers every objective, the route through the sewers, how to handle the Galvanized Mauler boss encounter, and what to expect when you come back up.
How to Unlock Subterranean Secrets in Lord of Hatred
Subterranean Secrets unlocks automatically once you finish Between Heaven and Hell. That quest ends at the entrance to the Temis Sewers after you follow the Hand of Akarat through the Promenade. There is no separate trigger, side step, or NPC to speak to — Subterranean Secrets begins the moment the previous quest closes.
It is the sixth main quest in Act VIII: Lord of Hatred, Chapter One (The False Prophet), and it sits directly between Between Heaven and Hell and The Queen and the Saint in the campaign sequence.
Subterranean Secrets Full Walkthrough
Step 1: Enter the Temis Sewers
You start at the sewer entrance in the Temis Promenade. Head straight in.
The sewers are dark and cramped, but the path forward is mostly linear. As soon as you enter, you start running into enemy groups. The primary threats here are rat-like monsters — fast, numerous, and aggressive. Do not let them swarm you. Clear packs as you go rather than trying to run past them.
Keep pushing forward along the sewer corridor. There are no branching paths that matter at this stage. Follow the quest marker and keep fighting through whatever spawns in your way.
Bug note: Some players have reported being unable to attack in the Temis Sewers, particularly on the Paladin class. If your abilities stop working after entering, exit the game fully and reload. Do not simply warp away — a full restart is the fix that resolves this. Blizzard is aware of the issue.
Step 2: Reach the Sunken Catacombs
After pushing through the initial sewer section, the environment shifts. The path descends deeper and opens into the Sunken Catacombs — an older, flooded structure beneath the sewers proper.
The enemy mix changes here. Alongside the rat enemies from the sewers, you begin encountering vengeful spirits. These hit harder and can be more erratic in their movement. Prioritize clearing them before focusing on the rats if both types are present in the same pack.
The Sunken Catacombs are also more maze-like than the initial sewer run. If you lose the path, follow your minimap and keep heading toward the quest marker. There are no secret areas that affect quest progression — just keep moving forward.
Step 3: Enter the Hall of Solitude and Speak with the Hand of Akarat
At the far end of the Sunken Catacombs, you find a chamber: the Hall of Solitude. The Hand of Akarat you followed from the Promenade is inside, along with other members of the order.
Approach and speak with him.
The conversation is short. What you witness is a ritual — the Hand of Akarat and those gathered with him willingly sacrifice themselves. This is not a trap or ambush in the traditional sense. They want this. The sacrifice is the point.
The ritual completes, and the sacrifices summon the Galvanized Mauler.
Step 4: Defeat the Galvanized Mauler
The Galvanized Mauler is the boss encounter for this quest. It is a large, physically powerful enemy and the most demanding fight in the False Prophet chapter up to this point.
What to know going in:
The Galvanized Mauler hits hard on direct strikes. Its core danger is close-range damage — if you let it get sustained contact, it drains your health fast. Watch for its attack windup animations and create distance when you see a heavy strike coming.
It does not have a massive suite of abilities, but what it has is punishing. Consistent pressure with burst windows between dodges is the safest pattern. Do not stand still.
If you are playing a ranged class like Warlock, kite the Mauler around the edges of the Hall and punish it between movement. If you are playing a melee class like Paladin, use your defensive skills on its big swings and commit to damage during the recovery frames.
After the Mauler goes down, the room is clear. The boss does not respawn.
Step 5: Head to the Plaza Overlook
With the Galvanized Mauler defeated, exit the Hall of Solitude. Follow the path leading out of the Sunken Catacombs and back toward street level.
The exit route brings you up into the Plaza of Queens, specifically to the Plaza Overlook — an open area in Temis above ground. Reach the waypoint marked on your map.
Once you arrive, Subterranean Secrets ends and The Queen and the Saint begins automatically. That quest continues the thread upward: now that you know what is happening beneath Temis, you and Lorath need to get to the queen.
Subterranean Secrets Quest Rewards
| Reward | Amount |
|---|---|
| XP | 10,013 |
| Gold | 480 |
| Next Quest | The Queen and the Saint (unlocked automatically) |
This is notably more XP than Between Heaven and Hell — reflecting the longer dungeon run and the boss encounter. The 10,013 XP is the verified reward from completing the quest.
Where Does Subterranean Secrets Fit in the Campaign?
Subterranean Secrets is quest six in Chapter One of Act VIII. Here is the full sequence for the False Prophet chapter:
- Solace Beyond Sight
- Last of the Horadrim
- Hatred’s Wake
- Crown of the Twin Seas
- Between Heaven and Hell
- Subterranean Secrets ← You are here
- The Queen and the Saint
The chapter is building toward a confrontation with whoever is truly driving Akarat’s movement in Temis. Subterranean Secrets is the moment that stops being a suspicion and becomes a confirmed threat.
Tips for Subterranean Secrets
Stock up before you go in. You are heading into a multi-stage dungeon with no waypoints until you exit. Make sure you have potions and consumables ready at the entrance. Running dry mid-dungeon slows everything down.
The sewers have no shortcuts. Every section of the Temis Sewers and Sunken Catacombs is a straight push forward. Do not waste time looking for shortcuts or alternate routes — there are none. Follow the marker.
Vengeful spirits in the Catacombs can be avoided. Not all packs in the Sunken Catacombs need to be cleared. If a group of spirits spawns off the main path, you can continue forward without engaging. Only fight what blocks your route or what you need to kill for XP.
Save burst skills for the Galvanized Mauler. The sewer enemies are manageable with basic attacks and low-cost abilities. Do not burn your cooldowns on regular mobs. Keep high-damage skills ready for when you reach the Hall of Solitude.
Check your build before this quest. If you are approaching this quest and feel under-equipped, our Lord of Hatred best starter build guide covers the most effective setups entering the mid-campaign. Also see our Warlock class guide or Paladin class guide if you are playing either of the new Lord of Hatred classes.
About Lord of Hatred
Lord of Hatred is the second major expansion for Diablo 4. It concludes the Mephisto storyline started across the base game and Vessel of Hatred, and takes players to the Skovos Isles — the ancient birthplace of the firstborn civilization and the former home of Lilith and Inarius, now ruled by the Amazon Queen and the Oracle.
The expansion introduces two new classes (Warlock and Paladin), the Horadric Cube crafting system, Talismans with set bonuses, a Loot Filter, and a full new campaign set across Skovos. Subterranean Secrets is one of the quests that makes the city of Temis — the main hub for the expansion — feel genuinely dangerous from the inside out.
You can pick up the expansion on Steam or Xbox. If you are just starting out, our tips before starting Lord of Hatred page covers what you should know before you dive in, and our full Lord of Hatred review is worth reading if you want a broad sense of what the expansion delivers.
FAQ: Subterranean Secrets — Diablo 4 Lord of Hatred
How do you unlock Subterranean Secrets in Lord of Hatred?
You unlock it by completing Between Heaven and Hell, the quest directly before it. That quest ends when you follow a Hand of Akarat through the Temis Promenade to the entrance of the Temis Sewers. Subterranean Secrets begins automatically from there with no additional steps.
Where are the Temis Sewers in Diablo 4 Lord of Hatred?
The Temis Sewers are located beneath the city of Temis in the Skovos Isles region. You access the entrance from the Temis Promenade at the end of the Between Heaven and Hell quest. The sewers connect down into the Sunken Catacombs further in.
How do you beat the Galvanized Mauler in Subterranean Secrets?
The Galvanized Mauler is summoned in the Hall of Solitude after the Hand of Akarat and his followers sacrifice themselves. It is a physically aggressive boss that deals heavy melee damage. The key is avoiding its sustained close-range attacks — dodge its heavy strikes, punish during its recovery, and save your high-damage cooldowns for this encounter rather than spending them on sewer enemies.
What are the rewards for completing Subterranean Secrets?
Completing Subterranean Secrets gives you 10,013 XP and 480 Gold. The next main quest, The Queen and the Saint, also unlocks automatically once you reach the Plaza Overlook.
What quest comes after Subterranean Secrets in Lord of Hatred?
The Queen and the Saint is the next quest. It begins at the Plaza Overlook in Temis, which is where Subterranean Secrets ends. That quest brings you back into the open city to deal directly with Queen Adreona and the full weight of what Akarat’s order has set in motion.
Why can’t I attack in the Temis Sewers?
This is a known bug affecting some players, particularly those on the Paladin class. If your character cannot use abilities or basic attacks after entering the sewers, exit the game entirely and reload. Warping to another location and back does not reliably fix it — a full restart does. The issue has been reported to Blizzard on the official forums.
Related Walkthroughs
- Chapter 1: The False Prophet — Full Walkthrough
- Between Heaven and Hell Walkthrough
- Crown of the Twin Seas Walkthrough
- Hatred’s Wake Walkthrough
- Last of the Horadrim Walkthrough
- Solace Beyond Sight Walkthrough
