Mortal Shell 2 Sanguine Caverns Walkthrough
Quick answer: Sanguine Caverns is the second Fainweald Corrupted Gate. Start at the Sanguine Shoreline Beacon, follow the Blood Caves to the Infected Gate, cleanse every Beacon, then fight The Lost Child. After the post-boss Beacon, the innermost chamber holds a Blackmarrow Key.

Official promotional screenshot: Steam / Cold Symmetry / Playstack
Route
- Open the Sanguine Caverns Corrupted Gate after you have a permanent Shell and preferably Magdalena's Ova packet.
- Activate Sanguine Shoreline, then stay on the Blood Caves line. Side tunnels hide Tarstones and materials; the Infected Gate is the story spine.
- Optional 1 Glimpse summon: Tiel, just before the arena.
- Fight from the Lost Child's side, never the mouth. Full plan: Lost Child boss guide.
- Cleanse the spawned Beacon (26 Ova in launch guides). Then check the innermost chamber for the Blackmarrow Key used on Marrow Keep sarcophagi.
Before you leave
- Lost Clotstone is the reported Ability reward for Obsidian Hammer / Veteran's Battle Axe.
- Next story gate in Fainweald is Prisoners' Domain.
- If the grab attack is eating you, swap to a faster weapon and stop fighting in front of the mouth.
Related guides
Evidence: Gate order and the post-boss Blackmarrow Key follow GameSpot's Lost Child notes and this site's boss page. Verified August 23, 2026.