Mortal Shell 2: How to Cleanse the Stonebled Gate Beacon and Get the Serpent Stone

The Stonebled Gate beacon sits at the mouth of the Sanguine Caverns in Mortal Shell 2, and cleansing it is the only way to open the Corrupted Gate behind it. Inside the beacon is a self-contained dungeon called The Hidden Keep, capped by a two-phase fight against Lucian, the Thirsting Knight. Clear it and you walk away with the Serpent Stone and the Ova needed to keep pushing forward.

Quick answer: Descend into The Hidden Keep using the Stonebled Gate beacon elevator, fight through the imps and Halberd Knights, then defeat Lucian in both phases. The Serpent Stone drops when his second phase ends. Cleanse the corruption and grab the three Ova to complete the beacon and open the gate.

Where the Stonebled Gate beacon is

The Stonebled Gate is found north of Fainweald, tucked inside a cave just before the Sanguine Caverns Gate. A trail of blood leads directly to it, so it is hard to miss once you are close. Cleansing this beacon is a hard requirement to reach the main boss waiting past the gate.

If you are approaching from the overworld, head to the Stones of Remembrance graveyard and cleanse the northernmost corrupted vines. Use the bone gate to cross the large chasm, follow the caverns north, then climb the steps to arrive at the beacon.

Reaching it from Widow’s Overlook

Start at the Widow’s Overlook beacon and run down the path leading away from it. Keep moving toward the narrow stone bridge ahead.

Player character running down a rocky path toward a narrow stone bridge from Widow's Overlook — Leaving the Widow’s Overlook beacon and heading down the path toward the stone bridge. Image credit: Cold Symmetry / via @SharkR

Deal with the two flying, bat-like enemies that swoop in along the route. They go down quickly, so clear them and keep pressing forward.

Player fighting a winged skeletal enemy in a grassy, root-covered outdoor area — Cutting down the winged enemies that harass you on the path out of Widow’s Overlook. Image credit: Cold Symmetry / via @SharkR

Cross the wooden bridge and continue through the rocky canyon. Check your map here to keep your bearings toward the Blackridge Cliffs.

Armored character running through a narrow rocky canyon with the HUD visible — Following the rocky canyon toward the Blackridge Cliffs. Image credit: Cold Symmetry / via @SharkR

Enter the Blackridge Cliffs and push through the swampy stretch. A large, spider-like bone enemy appears here; take it out before moving on toward the caverns.

Player facing a skeletal spider enemy with its red health bar showing overhead — The skeletal spider enemy guarding the swampy stretch in the Blackridge Cliffs. Image credit: Cold Symmetry / via @SharkR

Continue into the Sanguine Caverns overworld and follow the blood trail up to the Stonebled Gate beacon. Rest here to set your respawn point before entering.

Clearing The Hidden Keep

The Hidden Keep is a medieval, castle-styled dungeon reached by riding the elevator down from the beacon. Beacon dungeons are compact, so plan to fight through most of the enemies rather than looking for shortcuts.

Take the elevator to the bottom and go down the first flight of stairs. You will see two doorways. Enter the open one on the left first.

Inside, destroy the breakable boxes covering the cracked wall on the right and squeeze through the gap. Defeat the Deprived enemy near the growth, then check the growth to collect Laterite.

Return through the gap and exit. Approach the closed gate where the Halberd Knight is trapped and attack it to open the way. The knight strikes immediately, so be ready to dodge. Beat it and grab the Laterite from the growth behind it.

Back in the corridor, smash the boxes blocking the small room beside the knight’s area. Head inside, kill the Imp waiting there, and press the button on the wall in the left corner to open the passage ahead. Note that Imps are fast and have a long-range lunging grab, so do not treat them lightly.

Walk through the newly opened wall into the keep, where Imps and Halberd Knights are fighting each other. This brawl is not scripted and can end either way. Let it play out and pick off the survivors, or jump in and collect the Gloom yourself.

Keep going straight and cross the wooden bridge. It collapses behind you, dropping you into a square arena where Lucian, the Thirsting Knight, appears and attacks at once.

Beating Lucian, the Thirsting Knight

Lucian is a two-phase vampire-type miniboss who leans hard on fast lunge attacks that close distance in an instant. Prioritize dodging over parrying and keep moving through his combos so you never get cornered. He is weak to fire, and Curseblood works exceptionally well against him.

Setting Lucian on fire staggers him and freezes him in place while he burns, opening a long punish window. Stacking Burn with Curseblood deals heavy damage. Once his health drops to half, he bursts into bats and vanishes, and a Bone Gate opens leading toward the tower where his shadow drifted.

Traverse the Bone Gate to a cobblestone road, then go through the tunnel ahead. A gap in the left wall reveals the Ova inside a room. Entering it triggers the second phase, and Lucian starts this fight already at half health.

Phase	What changes	How to handle it
Phase 1	Fast lunges and quick attacks that rush you down	Dodge his approaches, set him on fire to stagger, and punish while he burns
Phase 2	Turns invisible at the start and strikes from the shadows	Apply Curseblood to make him pulse red and cancel the invisibility, then keep circling the arena

For the second phase, a weapon with wide swings and quick recovery helps a lot, since it keeps you from locking into long animations while he flickers in and out of sight. Imbue your weapon with Curseblood and your sidearm with Burn to stack both effects. Even without those, his invisibility is temporary; he re-materializes, stays solid for a few seconds, then fades again, so you can outlast it by running and dodging in circles. Defeat him here and the Serpent Stone drops.

Rewards and confirming the cleanse

After Lucian falls in the second phase, cleanse the corruption in the room and collect the three Ova to clear the beacon. That final step is what completes The Hidden Keep and cleanses the Corrupted Gate outside, opening the way into the Sanguine Caverns where a main boss waits.

Reward	Amount
Serpent Stone	x1
Glimpse	x1
Ova	x3

You will know the cleanse worked when the corruption around the beacon clears and its map icon changes to the cleansed state. The blocked loot around the beacon also becomes reachable, and the gate to the Sanguine Caverns is no longer sealed. Since none of the beacons are missable, you can always return later if you leave before finishing, but the Serpent Stone and the gate only unlock once Lucian’s second phase is done and the three Ova are claimed.