Mortal Shell 2: Blackmarrow Key Location Near the Abbey Entrance Beacon

Blackmarrow Keys are the currency for cosmetics in Mortal Shell 2, and the game never explains where they are or what they open. One of them sits in the Abbey area of Mammon, behind a combat trial and a short platforming section that most players walk straight past.

Quick answer: From the Abbey Entrance beacon in Mammon, work through Sester’s Refuge, cross the bridge, follow the wooden scaffolding to the Revenant Graves, clear the trial there, then jump across the white nest platforms into the ruined tower and open the stone chest.

What a Blackmarrow Key opens in Marrow Keep

The key has exactly one use. It unlocks the chests standing around the lift in Marrow Keep, and each chest holds a unique Shade — an alternate appearance — for one of the eight Shells. There are eight chests and eight keys hidden across a playthrough, so a completionist run can open every one of them.

Two conditions matter. A chest only opens if you have already recruited the Shell it belongs to, and the key is consumed the moment you use it. After unlocking a Shade, swap to it with the Change Shade option while resting at any Beacon.

Route to the Abbey Blackmarrow Key from Outskirts of Mammon

If you have not reached the Abbey yet, start at the Outskirts of Mammon beacon. If the Abbey Entrance beacon is already lit, fast travel there and skip to Step 4.

Leave the Outskirts of Mammon beacon and run through the swamp toward the white fabric portal. Dash through it to come out among the castle ruins.

Player character suspended between huge roots as black particles drift through the fog — The transition into the Abbey ruins. Image: Cold Symmetry

Push through the ruined cemetery and clear the armored enemies inside the stone hall. A sarcophagus here can be opened for the Tyrant’s Stone, which is optional but on the way.

Tyrant's Stone pickup prompt with the options to confirm or inspect the item — The Tyrant’s Stone pickup screen after opening the sarcophagus. Image: Cold Symmetry

Fight past the burning altar and continue until the Abbey Entrance beacon appears. Activate it. This is your checkpoint for the rest of the run.

Take the southeast stairs into the castle and pull the wall switch to raise the large iron gate.

Armored player character standing in front of the closed barred gate inside the castle — The barred gate that opens once the wall switch is pulled. Image: Cold Symmetry

Enter Sester’s Refuge, clear the enemies inside, and break the wooden structures blocking the stairs. Cleanse the Sester’s Refuge beacon while you are here so you have a closer respawn point.

Come out the far side, turn right, and deal with the Sester enemies guarding the bridge. Cross the bridge to the tower on the other side.

Follow the narrow wooden scaffolding that runs along the outer castle walls. It is tight and unrailed, so move slowly rather than sprinting.

Player crossing a narrow wooden walkway built into the cliffside beside the castle wall — The wooden scaffolding stretch leading toward the Revenant Graves. Image: Cold Symmetry

Reach the Revenant Graves and start the trial. The fight takes place in a fogged arena against a winged, shield-carrying enemy, and the platforms you need next do not appear until it is over.

Combat trial in the misty Revenant Graves arena against a winged shield-bearing foe — The Revenant Graves trial that gates access to the tower. Image: Cold Symmetry

Jump across the pale organic nest platforms toward the ruined tower. They are stable, but line up each jump before committing since a miss drops you back down.

Inside the tower room, open the stone chest. The Blackmarrow Key drops here. Use the same nest platforms to jump back out.

Note: the same tower area also contains an updraft that carries you back up to the bridge level, so you do not need to retrace the whole scaffolding walk if you drop down while exploring.

How to confirm you picked it up

Opening the chest triggers the item acquisition prompt, and the key then appears in your inventory as Blackmarrow Key under key items, with the description line about the Mether’s bones and Gloom. If it is not listed there, the chest was not actually opened.

Back at Marrow Keep, walk up to a Shade chest by the lift. If the interaction prompt does nothing, the Shell tied to that chest has not been recruited yet — pick a different chest or unlock that Shell first. On a successful unlock the key disappears from your inventory and the Shade becomes selectable at any Beacon.

Other Blackmarrow Key locations

Because each chest consumes a key, the Abbey one alone covers a single Shade. These are the other confirmed sources.

Source	How to get it
Abandoned Outpost, Mammon	Night Mode only. The Collector, a night merchant south of the beacon, sells one for 1,500 Gold.
Shrine of Sorrows	Night Mode only. Clear the first-person dungeon southwest of the Mushroom Village beacon.
Mushroom Village	At night, past the bonfire and across the bridge, accept the large mushroom’s invitation and solve its non-combat puzzle.
Desolate Keep	Secret dungeon under Marrow Keep. Take the Slayer Seal, break the arrow-marked wall in the training chamber, free the chained chalice, and use Commune with Chaos. Reward sits at the end of the dungeon.
Child’s Feeding Ground	Beat the Lost Child in Sanguine Caverns, cleanse the beacon, then re-enter the dungeon and open the chest in the secret room where the Ova was.

Keys are not the only route to new Shades. Pre-order and Devout Edition upgrade buyers receive their own exclusive appearances, which do not consume anything.

The Abbey key is one of the more approachable finds of the eight, mostly because the route runs through beacons you will light anyway. Cleanse Sester’s Refuge before starting the Revenant Graves trial and the whole detour costs you a few minutes rather than a long walk back.