The Tarstone modifier items in Mortal Shell 2 have their own leveling mechanism that is completely independent of the Gloom required to upgrade the stats of The Harbinger herself. The distinct leveling system also requires the use of the TarForge and Tarcores in order to Temper or upgrade every Tarstone after maxing out their individual XP bars for each level.
This Mortal Shell 2 guide explains how Tarstone leveling is accomplished and how to get the Tarcores required to Temper them.
How To Farm Tarstone XP
The level 1 Tarstone XP bar requires 10,000 points to accumulate in order to reach level 2, and will take a great deal of grinding to accomplish. Fortunately, unlike Gloom, any earned Tarstone XP is not lost on death and is also automatically tallied for every kill, but only as long as the Tarstone is actively equipped.
For maximum effect, you should equip every Tarstone you possibly can to the upper limit of ten. This includes the four applicable to the Shell, and the two each for Ability, Combat, and Infusion.
Once a Tarstone reaches its maximum XP limit, any further Tarstone XP earned is wasted on it, as it does not carry forward to the XP bar of the next level. So be sure to swap them out for another unleveled Tarstone so as to avoid wasting your efforts. There is also another reason why you should be grinding Tarstones to higher levels even if you do not really want to make use of their abilities, and which will be touched on below.
As for actually farming Tarstone XP, this really is a matter of pure combat. So, find a Beacon with the most lucrative run of enemies that you can blast and cleave through as quickly as possible, and just keep resting at the Beacon in order to reset them, rinse, and repeat.
How To Get The Etching Needle And Upgrade Tarstones
Once you have filled a Tarstone’s XP bar at level 1, you can Temper it to level 2 proper at the Tarforge in the Marrow Keep. But this option is unavailable until you acquire the Etching Needle and give it to Franz the TarForge Smith.
The Etching Needle is located in a chest around the area where you battle the boss Magdalena, the Lady of the Woods. Beginning at the Sunken Bridge Beacon, run across the bridge into the sheep pen where the The Wandering/Tarblighted Shepherd miniboss is battled. Smash through the crates in front of the wood gate straight ahead, and then cross another bridge to find Ruk, as well as the Etching Needle chest.
Now wrap this up by taking it to Franz and unlocking the Temper Tarstones menu. Each Tarstone upgraded to level 2 will cost a hundred Gold Coins as well. Once done, the level 2 XP bar of 20,000 points is unlocked, allowing you to equip it for further Tarstone XP grinding in order to reach level 3.
Fully Tempering a Tarstone to level 3 adds another resource to the upgrade requirements: 6X Tarcores, aside from an increase to 150 Gold Coins.
How To Get Tarcores Fast
The only way to get the required Tarcores is by actively Tempering Tarstones at the TarForge. When you upgrade a Tarstone from level 1 to level 2, you also get a single Tarcore in return. With six Tarcores required to then upgrade a Tarstone from level 2 to level 3, you will need to grind XP and temper at least six individual Tarstones to level 2 in the first place.
And this is why it is important to farm Tarstone XP even for Tarstones that hold no particular interest for your build, initially at least. Equally important is efficiently swapping out Tarstones that have reached their maximum accumulated XP, just until you can head back to the TarForge and Temper them to the next level properly.
Fortunately, the Tarcore return on investment scales when you Temper a Tarstone from level 2 to level 3: you will receive three Tarcores back for the six that you spent in the first place. Now you only have to grind Tarstone XP and Temper another three level 1 Tarstones in order to accumulate enough Tarcores to Temper a single level 2 Tarstone. And so on and so forth.
This closed loop of Tarcores earned from Tempering Tarstones implies that you should be cautious and choosy about exactly which Tarstones you finally upgrade to level 3.
That is everything there is to know about upgrading Tarstones and acquiring Tarcores in Mortal Shell 2.
