Quick answer
To temper Tarstones normally, restore the Temper Tarstones function at the Tarforge by bringing Etching Needles back to Franz in Marrow Keep. Keep a Tarstone slotted on equipment you are actually using, kill enemies to fill its XP bar, then temper it when eligible. After the Week 1 Update, Tarcores are no longer finite and Tarstones yield more Tarcores when broken — with a compensation cache for already-leveled stones.
Unlock the Tarforge function
Current launch routes place the Etching Needles in the Glutted Mire / Magdalena-side progression. Bring them to Franz at the Marrow Keep Tarforge and the Temper Tarstones menu option becomes available.
The Tarforge has other upgrade parts for melee weapons, sidearms, smelting and the late upgrade cap, but you do not need all of them just to understand Tarstone leveling.
How Tarstone XP actually works
A stone needs to be equipped/slotted on equipment you are carrying for its XP to grow from kills. You do not need to trigger the active effect every time.
This creates a useful leveling trick: keep a stone equipped while doing normal exploration even if it is not the centerpiece of the current encounter.
Temper only after the bar is ready
When the Tarstone’s XP requirement is filled, return to the Tarforge. The temper menu will show eligible stones and the next material/coin cost.
Current launch guides publish exact XP/Tarcore thresholds, but those are economy values that can be patched. This guide intentionally tells you where the requirement is displayed in-game rather than pretending an August 20 number is permanent.
Week 1 Update changed Tarcore planning (read this)
Two official changes alter the “be careful with Tarcores” advice:
- Tarcores are no longer finite. The developer notes state all Tarstones can now be upgraded in a single playthrough.
- Tarstones yield more Tarcores when broken. If your save already contains leveled-up Tarstones, a compensatory cache of Tarcores is added to your inventory so you are not behind the new economy.
So the old “max only the stones you use” constraint is obsolete — but the practical advice to level in priority order still holds, because tempering a stone you never slot is wasted XP time, not wasted Tarcores.
Snapshot of the new Fragile economy
Fragile Tarstones (including the reworked Justiciar’s and Gloombound) break after losing durability and drop a Tarcore on break. That means:
- Fighting with Fragile stones gives you a rebuilding economy, not just a consumable.
- They are not unique — several can be found per playthrough (enemy drops, dungeon rewards, Merrick’s shop).
Level what you use, in this order
- The stone(s) that create your actual combat loop.
- A second set for the alternate weapon/sidearm you swap to.
- A Glimpse Stone for combat-drip Glimpses while you explore.
Last verified: 2026-08-30.