Mortal Shell 2: Monarch’s Vestige Tarstone Location

Monarch’s Vestige is one of the Infusions Tarstones in Mortal Shell 2, and it turns your sidearm into a Phantom damage source for a burst of shots. It is not sitting in a chest somewhere — it is a boss drop, and the boss is locked behind a key you have to dig out of a village hut first.

Quick answer: Kill Bor, the Deluded Monarch, in the cave at the end of the Kingdom of Fools. To reach him, grab the Strange Village Key from a chest hidden behind a wooden barrier in one of the village huts, then use it on the large wooden gate leading to the cave.

Monarch’s Vestige effects and Resolve cost

Monarch’s Vestige belongs to the Infusions category, which means it slots into a sidearm rather than a melee weapon or a shell. Activating it spends 20 Resolve and coats your shots in Phantom until the infusion runs out. Each upgrade level stretches how long that coating lasts, ending with an infusion that never expires.

Level	Effect
Level 1	Consume 20 Resolve to infuse your Sidearm with Phantom
Level 2	Infusion lasts for 4 shots
Level 3	Infusion lasts for 8 shots
Level 4	Infusion is permanent

Not every ranged weapon accepts it. The Salvaged Trebuchaxe is listed as a compatible sidearm, so if the Tarstone appears greyed out in your loadout, swap sidearms before assuming something is broken. The Trebuchaxe itself sits at the end of the Ravaged Hideout dungeon in Fainweald, which opens up after you kill the Bloodcursed Lithopod outside the Citadel of Penance.

Route to Bor, the Deluded Monarch

The whole run starts from a single fast travel point in the Ruins of Mammon and takes only a few minutes if you skip the optional fights. The awkward part is the key, because the chest holding it is walled off and easy to walk straight past.

Fast travel to the Outskirts of Mammon beacon. From there, run through the open ground ahead and drop down the cliffside instead of taking the long way around. Most of the enemies here can be ignored outright.

Push on to the graveyard area below and clear the handful of enemies that come at you. One of the walls here is fake — hit it to break through and open the chest behind it. That chest holds the Tyrant’s Stone, which grants access to a special Heavy Combo Finisher.

Player character trading sword blows with an enemy in the ruined graveyard courtyard — Clearing the graveyard ruins before breaking the hidden wall that hides the Tyrant’s Stone chest. Image: Cold Symmetry

Carry on into the dark village stretch, the Kingdom of Fools. Visibility is poor and enemies sit tucked between the huts, so move slowly and deal with anything that closes in rather than sprinting past groups.

Player pushing past a candlelit altar while an enemy attacks in the dark village — The candlelit altar area partway through the dark village leg of the route. Image: Cold Symmetry

Search the huts as you go. Inside one of them is a wooden barrier blocking a small alcove — destroy it and open the chest behind to pick up the Strange Village Key. Larger foes patrol this part of the village, so expect at least one drawn-out fight while you check the buildings.

Fight against a red tentacled enemy with its health bar shown on screen — A red tentacled enemy guarding the village huts, complete with its own health bar. Image: Cold Symmetry

Backtrack to the large wooden gate you passed earlier and interact with it while holding the key. The gate opens permanently, revealing the path down into the cave.

Walk into the cave to trigger the fight with Bor, the Deluded Monarch. Beating him drops the Monarch’s Vestige Tarstone on the spot.

Boss encounter against Bor, the Deluded Monarch inside a dark cavern — The Bor, the Deluded Monarch boss fight in the cave beyond the locked gate. Image: Cold Symmetry

Note: the same fight can also be approached from the Abbey Entrance beacon side of the map, so if you have already cleansed that beacon, you may reach Bor without the run described above.

Confirming the drop and equipping the infusion

Open the Tarstones menu after the fight. Monarch’s Vestige should show up under Infusions at Level 1 with an XP bar reading 0 / 10000, which is the progress it needs before an upgrade becomes available. Slot it into the Sidearm Infusion socket of a compatible sidearm.

To check it works in the field, build Resolve and trigger the infusion. Your Resolve meter drops by 20 and a Phantom indicator appears alongside your sidearm, confirming the coating is live. If nothing happens, the two usual causes are having under 20 Resolve or having the stone equipped to a sidearm that does not support it.

Tarstones menu with Monarch's Vestige selected and the four-shot infusion line highlighted — Monarch’s Vestige in the Tarstones menu, with the “Infusion lasts for 4 shots” upgrade line highlighted. Image: Cold Symmetry

Upgrading Monarch’s Vestige at the Tarforge

Levelling this Tarstone past its base state requires the Etching Needle, a quest item that expands what the Tarforge in Marrow Keep can do. Hand it to Franz and the higher upgrade tiers unlock.

The Etching Needle sits in a chest just before the Magdalena, the Lady of the Woods boss fight. Once you spot Ruk past the bridge, jump down through the opening and turn right before entering the tunnel — a small side area holds a bone chest with the needle inside.

After that, the stone levels through use. Keep Monarch’s Vestige equipped and kill enemies until its XP bar fills, then return to Franz and pay the Coin cost to push it to the next tier. Repeat until the infusion becomes permanent, at which point the 20 Resolve activation stops being a running expense.

Because Bor sits at the end of a short, self-contained stretch of the Kingdom of Fools, this is one of the cheaper Phantom sources to pick up early in the Ruins of Mammon — and worth grabbing on the same trip as the Tyrant’s Stone, since both sit along the same path.