Mortal Shell 2: How to Upgrade Tarstones at the Tarforge

Tarstones are equippable stones in Mortal Shell 2 that add passive effects and change how the Harbinger fights. Each one holds four levels, and every level makes its effect stronger. To reach those higher levels, you need to unlock the Tarforge’s Tarstone option, build up experience on the stone itself, and pay the right materials.

Quick answer: Grab the Etching Needles from the Glutted Mire and hand them to Franz at the Tarforge in Marrow Keep. Then keep a Tarstone slotted in an equipped weapon until it maxes its XP and shows “Tarstone Temper Ready,” and use the Tarforge to spend Coins (and later Tarcore) on the upgrade.

Unlock Tarstone upgrades with the Etching Needles

The Tarforge cannot temper Tarstones until you bring Franz the Etching Needles. This is a one-time key item that permanently adds the Tarstone option to the forge. Coins are the currency you spend after that.

The Etching Needles sit in the Glutted Mire, the Cleansed Gate dungeon in the southeast part of Fainweald, next to the Mushroom Village Gate beacon on the eastern side of the map. Work through the swamp until you reach the Sunken Village beacon.

Cross the rope bridge past the Sunken Village beacon and defeat the Tarblighted Shepherd mini-boss.

Break the wooden boards blocking the gate and squeeze through the gap. You will pass Ruk, who warns about the boss ahead.

Cross the long bridge and open the unguarded chest sitting in plain view between a tree and a lit torch. This holds the Etching Needles.

The chest sits just before the Magdalena, Lady of the Woods boss fight. You can grab the item and turn back to the last beacon without fighting her, and you can return to this spot later if you skipped it.

Fast travel back to Marrow Keep, speak to Franz the Tarforge Smith, and choose “Give Etching Needles.” The next time you interact with the Tarforge, the Temper Tarstones option will be available.

How Tarstones earn XP

A Tarstone only gains experience while it is slotted into a weapon or sidearm you have equipped. Kills are what feed it, so any enemy-dense area builds XP quickly. You do not have to actively trigger the Tarstone’s effect during combat, only keep it slotted.

Some Tarstones only work with specific weapons and will not slot into everything, so check compatibility before you start grinding. When a stone fills its current XP bar, the game shows a “Tarstone Temper Ready” prompt, which is your signal that it can be leveled at the Tarforge.

Tip: Night Mode raises the Coins and Gloom you earn while making enemies deadlier, which speeds up Tarstone farming. Toggle it by talking to Thestus, the NPC who appears after you light the extinguished lantern on top of Marrow Keep with the Gloombound Flame.

Upgrade cost: Coins, XP thresholds, and Tarcore

Unlike weapons and sidearms, Tarstones do not need Ventrium or other smithing stones. They run on Coins plus the XP you bank on each stone. The catch is the higher tiers, which also demand Tarcore, a material you earn by tempering Tarstones in the first place.

Upgrade step	XP needed	Cost
Level 1 → 2	10,000 XP	100 Coins, and grants 1 Tarcore
Level 2 → 3	20,000 XP	Coins plus 6 Tarcore
Higher levels	Increases each tier	Rising Coin cost

Because a single level-up only ever hands you one Tarcore, and reaching level 3 costs six, you have to level several Tarstones from level 1 to level 2 to stockpile enough. Spend the extra Tarcore on the stones you actually want maxed, even if that means raising some stones you do not plan to keep.

Upgrade a Tarstone at the Tarforge

The Tarforge lives in Marrow Keep, the central hub you reach through discovered Beacons. Once Franz has the Etching Needles, the process is short.

Slot the Tarstone you want to raise into an equipped weapon and kill enemies until it hits the level-up threshold and displays “Tarstone Temper Ready.”

Return to Marrow Keep and stand at the Tarforge. Choose “Temper Tarstones” from the menu.

Select the maxed-out stone and confirm the upgrade, paying the Coins (and Tarcore at the higher tiers). The stone jumps to its next level, and its effect improves right away.

You will know it worked when the Tarstone’s level increases in the menu and its listed effect changes to the new tier. After an upgrade, the XP bar resets, so you need to earn the next threshold before you can temper the same stone again.

Why an upgrade won’t trigger

If the Tarforge won’t let you level a stone, one of these is almost always the reason.

You haven’t given the Etching Needles to Franz yet, so the Temper Tarstones option is still locked.
The Tarstone hasn’t reached its XP threshold. It only earns XP while slotted in an equipped weapon during kills.
You don’t have the Coins, or at level 3 and beyond, the six Tarcore the tier requires.
The Tarstone was placed in a weapon it isn’t compatible with, so it never gained XP.

Once the needles are handed over, the whole loop becomes routine. Keep a stone slotted while you clear content, watch for the “Tarstone Temper Ready” prompt, and cycle back to the Tarforge to bank the level whenever you are near Marrow Keep.