Mortal Shell 2: Castigator’s Keep Walkthrough and All Secrets

Castigator’s Keep is the hub of the Ruins of Mammon, and it hides more than its ruined walls suggest. Four dungeons branch off a single beacon, a sidearm sits underneath the bridge you walked in on, and one caged NPC will hand you a pile of Gloom if you show up wearing the right shell.

Quick answer: Cleanse the Castigator’s Keep Beacon, clear Viletongue’s Domain, Blackwell Cavern, the Alchemist’s Workshop, and the Hall of Murmurs, grab Map of Mammon [3] from the statue shrine, then switch to the Lazlo shell and pay Egon two 10,000 Gloom tributes to get 40,000 Gloom back.

How to reach Castigator’s Keep

Castigator’s Keep sits directly after the Outskirts of Mammon. Follow the Road to Absolution west through the ruins, cross the long bridge between the white bone pillars, and pass through the Bone Gate at the end of it. Armored and shielded enemies patrol the walkway on the far side, so clear the bridge before you start exploring.

The Keep is a junction, not a dead end. It links to the Lonesome Spire on one side and the Vestige of Infinity on the other, which makes the beacon here one of the more useful fast travel points in Mammon.

Player character crossing a grassy, rocky stretch of the Ruins of Mammon with the HUD visible — The open plains between the Keep’s walls and its outer gates. Image: Cold Symmetry

All four dungeons in Castigator’s Keep

Four separate dungeons feed off this one area, and each one holds a distinct reward. Clearing all four is what “100%” means here.

Dungeon	Entrance	Main reward
Viletongue’s Domain	Inside the Castigator’s Keep Beacon	Viletongue Hedron, Glimpse, Ova x3
Blackwell Cavern	Below the bridge you use to enter the area	Triarch Repeater sidearm
Alchemist’s Workshop	The stretch that connects the Keep to the Lonesome Spire	Clockwork Shardstone, Shepherd Totem, Dorsalite
Hall of Murmurs	Inside the Keep, near Ruk and his map fragment	Chest loot at the end of the tunnel

Cleanse the beacon and clear Viletongue’s Domain

Enter the Keep and climb the stone stairs to reach the upper ruins. The Castigator’s Keep Beacon sits at the top. Revitalize it first so you have a respawn and fast travel point before anything else.

Drop into the underground passage at the beacon and ride the elevator at the end of the path down into Viletongue’s Domain. A Wraith blocks the corridor ahead. Kill it, then drop into the room below and deal with the two Foul Knights waiting there.

From your landing spot, turn left and climb to the upper level. Another Wraith guards this stretch. Past it is a tomb with a short passage running behind it.

Go through the door to the right of the tomb. Inside you’ll find a gate with its lever missing and a Strange Concoction on a table. Drinking it summons Viletongue Batushka and inverts your movement controls, so hold back to walk forward for the duration of the fight.

Beat the boss to collect the Sage’s Gate Lever and the Viletongue Hedron. Slot the lever into the gate to open the path, then cleanse the corruption and take the Ovum. The beacon counts as cleared once that Ovum is in your hands.

Viletongue Batushka boss tips

Batushka has high poise, so light attack combos will not stagger it and only leave you exposed. Keep your distance from the long, lashing tongue swings, use Harden or a well-timed Perfect Guard to break its pressure, and hit it during recovery frames before backing off again. Trading blows is the fastest way to lose this fight.

Blackwell Cavern and the Triarch Repeater sidearm

Blackwell Cavern runs underneath the bridge that brought you into the area. Take the elevator down and follow the tunnels in; the location banner confirms you’re in the right dungeon.

Blackwell Cavern location banner appearing as the player steps into the dungeon — The Blackwell Cavern banner drops as you enter the tunnels below the bridge. Image: Cold Symmetry

The cavern is packed with white-glowing phantom figures that swarm in the dark. Thin them out before you go for the pickup, because the Triarch Repeater sits in a broken crate deep in the tunnels and grabbing it mid-fight is how most runs end. Once the room is clear, loot the crate to add the sidearm to your kit.

Player swinging a drawn weapon at enemies inside the rocky Blackwell Cavern tunnels — Clearing the phantoms in Blackwell Cavern before going for the Triarch Repeater. Image: Cold Symmetry

Ride the elevator back up when you’re done. The route out returns you to the Keep’s walkways, and enemies will have respawned along the way.

Map of Mammon [3] location

Near the beacon there’s a lever that opens a gate down into the lower ruins. Pull it, fight through the enemies below, and head for the large stone statue ringed by kneeling figures. Interact with the shrine at the statue’s base to receive Map of Mammon [3], which fills in this chunk of the region on your map screen.

Map screen open on the MAP tab showing discovered areas and location markers — The map screen after picking up a Map of Mammon fragment, with markers filled in. Image: Cold Symmetry

Note: a second map fragment is claimed from Ruk, who is found inside the Keep close to the Hall of Murmurs entrance.

Alchemist’s Workshop: illusion wall, reagent, and the Clockwork Shardstone

The Alchemist’s Workshop is reached from the side of the area that runs toward the Lonesome Spire, past bone gates and suspended bridges. Mutated enemies fill the lab itself, and a Dorsalite sits among the alchemical sketches and diagrams once the room is clear.

Two things gate progress here. One is a hidden side room behind an illusion wall, which you reveal by striking it. The other is the gap in the floor that has no visible bridge. Drink the alchemical reagent sitting on the bench and the bridge stabilizes, letting you cross through the red mist beyond. Skipping the drink means the crossing simply is not there.

Push on to the siphoning chamber, where four Glimpses and a Synaptic Vessel are waiting. Pull the lever, kill the creature penned behind the bars to take the Shepherd Totem, then open the chest for the Clockwork Shardstone.

Hall of Murmurs elevator route

Back inside the Keep, open the nearby gate and ride the elevator down to reach the Hall of Murmurs. A worm-like enemy guards the chamber at the bottom; kill it and open the chest it was protecting. There’s also an outer gate lift operated by a switch on a wooden pillar, which permanently connects the upper and lower halves of the area and saves a long run on repeat visits.

Player drawing a bow inside a dark stone chamber with health and ammo HUD showing — Ranged pressure works well in the tight stone chambers below the Keep. Image: Cold Symmetry

Egon’s Gloom trade with the Lazlo shell

Egon is caged in the ruined tower above the Keep’s courtyard, and he’s a relative of Lazlo. He asks for Gloom tributes, but the exchange only opens up when you speak to him in the correct body.

Rest at the Castigator’s Keep Beacon and change your shell to Lazlo. Any other shell and Egon’s tribute dialogue will not progress.

Talk to Egon and hand over 10,000 Gloom. Exhaust the dialogue, then offer a second tribute of 10,000 Gloom.

After the second payment he returns 40,000 Gloom, a net gain of 20,000. You’ll see the currency counter jump the moment the exchange resolves — that’s your confirmation the questline moved forward. Switch back to your usual shell at the beacon afterward.

Full pickup checklist for Castigator’s Keep

Item	Where to get it
Synaptic Vessel	Up the stone stairs immediately left of the Keep entrance
Synaptic Vessel	On the courtyard floor in the middle of the Keep
Unstable Stone	Among the giant rocks ringed by wooden platforms
Triarch Repeater	Broken crate deep in Blackwell Cavern
Map of Mammon [3]	Statue shrine in the lower ruins, behind the lever-operated gate
Sage’s Gate Lever + Viletongue Hedron	Dropped by Viletongue Batushka
Dorsalite	Alchemist’s Workshop lab, near the sketches
Shepherd Totem	Behind the bars in the siphoning chamber
Clockwork Shardstone	Chest in the siphoning chamber past the reagent bridge

Synaptic Vessels are worth spending at the beacon rather than hoarding, since they improve Mether’s Pulse efficiency.

Common reasons a step doesn’t trigger

The gate in Viletongue’s Domain stays shut until you place the Sage’s Gate Lever, which only drops from Viletongue Batushka.
Viletongue Batushka never spawns unless you drink the Strange Concoction on the table in that room.
The Alchemist’s Workshop gap cannot be crossed without drinking the alchemical reagent on the bench first.
Egon will not take a tribute unless you are wearing the Lazlo shell.
The lower ruins with the statue shrine stay sealed until you pull the lever near the beacon.

With the beacon cleansed, all four dungeons emptied, and Egon paid off, Castigator’s Keep is finished as a stop and useful as a base. From here the battlements lead across a rope bridge into the Vestige of Infinity, while the opposite route climbs toward the Lonesome Spire — both of which are far easier to tackle now that you can fast travel back to a cleared beacon.