Mortal Shell 2: How to Cleanse the Castigator’s Keep Beacon

The Castigator’s Keep beacon sits at the top of the Castigator’s Keep ruins in the center of the Ruins of Mammon. Cleansing it drops you into Viletongue’s Domain, a compact mini-dungeon that ends with a locked gate, a missing lever, and a boss fight where your movement inputs are flipped.

Quick answer: Enter the beacon, ride the elevator down, fight your way to the room with the lever-less gate, drink the Strange Concoction on the table to summon Viletongue Batushka, kill it for the Sage’s Gate Lever, fit the lever to the gate, then cleanse the corruption and collect the Ovum.

Where the Castigator’s Keep beacon is in the Ruins of Mammon

Head for the Castigator’s Keep ruins in the middle of the Mammon map. From the entrance, keep right and climb the stone stairs. The beacon is waiting at the top.

Interact with it and pick Cleanse Beacon. That option only appears on corrupted beacons, and choosing it teleports you inside rather than fast travelling anywhere. The other menu entries — Level Up, Change Shell and Equipment, Mether’s Pulse, Mether’s Breath, Return to Marrow Keep, and Leave — stay available before you commit, so sort your Shell and loadout first.

Route through Viletongue’s Domain

Run down the corridor past the beacon entrance. There’s a sarcophagus along the way — smash it for 1,000 Coins before you move on.

Armored Harbinger carrying a large axe steps through a doorway into a torchlit cavern — The opening corridor beneath the Castigator’s Keep beacon. Image: Cold Symmetry

Take the elevator at the end of the path down. The area name “Viletongue’s Domain” appears on screen once you arrive at the bottom.

The Viletongue's Domain area title appears on screen as the player moves through a dark passage — Viletongue’s Domain announces itself once the elevator reaches the bottom. Image: Cold Symmetry

Follow the path and kill the wight waiting ahead of you, then drop down the ledge into the cave below. Two heavier armored enemies are stationed at the landing point, so don’t drop in with low Resolve.

Clear the cave skirmish. Your sidearm helps thin out the group before they close in. There’s Ventrurium on the ground here along with loose Coins and Glimpse pickups.

Fire (Sidearm) prompt on screen as the player aims at an enemy inside the cave arena — The sidearm prompt during the cave fight, where the Ventrurium pickup is found. Image: Cold Symmetry

From where you dropped in, turn left and climb the ledge to reach the upper area. One more wight patrols up here.

Player swings at an enemy with a red health bar in a dimly lit cavern — The wight guarding the upper ledge on the way to the tombstone. Image: Cold Symmetry

Past the enemy you’ll find a tomb with a readable inscription. It’s the game telling you what’s coming: “The Great Sage, Batushka, welcomes all into his hall. Do not fear. Forget what you think you know. Truth will only come to those that embrace confusion.”

Go through the door to the right of the tomb, down the short passage, and into the room beyond. Inside is a gate you can’t open — interacting with it just returns “The lever is missing.”

Player faces a barred wooden door with an on-screen OPEN prompt — The door leading into the room that holds the lever-less gate. Image: Cold Symmetry

Drink the Strange Concoction to trigger the boss

The lever isn’t hidden somewhere in the dungeon. It’s carried by the boss, and the only way to summon that boss is to drink from the candle-lit table in the same room as the gate. Interacting with it brings up a “DRINK STRANGE CONCOCTION?” prompt with Yes and No options.

Choose Yes and Viletongue Batushka appears. There is no way to skip this fight and still open the gate.

Note: Rest, restock, and swap equipment before you touch the table. Once the concoction goes down, the fight starts immediately in a cramped room.

Beating Viletongue Batushka with inverted controls

The concoction flips your movement inputs for the duration of the encounter. Pushing forward walks you backward, pushing left goes right, and every dodge lands in the opposite direction to the one you intended. That’s the entire gimmick, and it’s what makes an otherwise moderate fight dangerous.

Player swings a heavy weapon at Viletongue Batushka in a candlelit chamber — The Viletongue Batushka fight, where your movement inputs run backward. Image: Cold Symmetry

Lean on defensive options rather than repositioning. Harden and Perfect Guard both work off timing instead of movement, so they stay reliable while your directional inputs lie to you. Batushka has high poise, and basic light attack chains won’t stagger it, so trading combos is a losing play.

Watch the reach on its tongue attacks. Keeping distance is harder than usual because backing away requires holding forward, so pick a spacing early and commit to it rather than constantly adjusting. Break its pressure with a timed guard, punish the recovery window, then reset.

Everything you collect in Viletongue’s Domain

Item	Where it comes from
1,000 Coins	Sarcophagus in the entry corridor
Ventrurium x1	Ground loot in the cave fight
Coins and Glimpse pickups	Scattered through the domain and dropped by enemies
Sage’s Gate Lever	Viletongue Batushka drop
Viletongue Hedron x1	Viletongue Batushka drop
Ova x3	Behind the gate, at the end of the dungeon
Glimpse x1	Beacon cleanse reward

Fit the lever and confirm the beacon is cleansed

With the Sage’s Gate Lever in hand, walk back to the gate in the same room and install it. The message “A gate has lifted” confirms the path is open.

Go through and use the Cleanse Corruption prompt on the growth beyond the gate.

Take the Collect Ovum prompt. You’ll get a “NEW OVUM FOUND” notification followed by a “Collect Ovum and return to beacon?” confirmation.

Accept, and you’re pulled back out to the surface. The on-screen “BEACON CLEANSED” message with the Castigator’s Keep name underneath is your confirmation that it’s done.

Back in the overworld, the black tendrils around the beacon are gone and its map icon changes to the cleansed version. If you ever need to double-check later, the Mether’s Breath fast travel list shows cleanse status by icon, which is useful because beacons tucked inside Gates don’t appear on the world map at all.

Why the cleanse didn’t complete

Two things stop this beacon from registering. The first is walking away after killing Batushka without installing the lever — the boss drop alone doesn’t count as progress, and the gate stays shut. The second is opening the gate but leaving before taking the Ovum, since the beacon only flips to cleansed once you accept the return prompt.

If you die inside, you respawn at your last beacon and the regular enemies come back, but the dungeon layout and the Strange Concoction are unchanged. Nothing here is missable, so a wipe just means walking the route again.

Castigator’s Keep is one of 49 beacons in the game, 46 of which can actually be cleansed — Marrow Keep, Widow’s Overlook, and Outskirts of Mammon come pre-cleansed. Every Ova in a playthrough comes from cleansing these, so clearing Viletongue’s Domain feeds directly into the 168 Ovum you need before Marrow Keep will open the Unfound Path.