Mortal Shell II Walkthrough — Ashen Sanctum (Blue Flames, Sonier & Sir Isaac)

The Ashen Sanctum is the citadel's inner sanctum: a short chapter built around blue-flame safety lamps, two Beacons, and the scholar prince at the end of it. It also secretly opens the endgame road.

In through the gate

Enter the Gate of Infinity and run the sanctum's opening road, clearing mobs. At the marked area, clear the pack, then double back: up the stairs, extinguish the blue flame, and open the chest for the Summoning Stone.

Return through the gap ahead, clear the mob pack, and loot the Backplate Stone. Continue up the road to the top, then descend the long drop-chain to the platform where the Bastille Annex Beacon unlocks.

The immobile sanctuary

Cleanse it and enter the Mute Sanctuary: light the blue flame here — this one is friendly, granting invulnerability — clear its wave, then its successor on the road beyond.

The left road hides a portal: cross it for the Ram-Head Totem. Ride the elevator to the platform atop the great creature, clear the mobs, and open the Immovable Blade Stone chest. Cleanse the Ova, rest — and a cutscene returns you to Marrow Keep, unlocking the Unfinished Path endgame region. (Teleport back; the sanctum is not finished with you.)

Sonier and the scholar prince

Return to the Bastille Annex and take the stairs forward: fight, extinguish the blue flame first, then the elite Gloom-Seeker Sonier — his Sonier Fragment drops on death. Ride the elevator up, take the slope, and exit into the fork: left unlocks the Bastille Courtyard Beacon.

Cleanse it, face the Servant of the Scholar Prince, and deliver the Ova. Ride the portal forward — Lazlo can be summoned here — and enter the arena of Sir Isaac, the Scholar Prince. Kill him for the Scholar's Wormstone, and the Scholar Prince's Chamber Beacon unlocks. Cleanse it, deliver the Ova, and return to Marrow Keep: the citadel's interior is yours.

Keep reading:

• The Ending Walkthrough
• Faded Citadel Walkthrough
• Lazlo, the Justicar — Royal Crypt Boss Fight