Quick answer
Tarstones are the main build-customization layer beyond your Shell and weapons. They fall into Support, Combat, Infusion, Ability roles plus the new Fragile class added in the Week 1 Update: Fragile Tarstones lose durability and break — yielding a Tarcore when they shatter. Fragile stones are not unique and can be found multiple times per playthrough.
The five practical Tarstone roles
Support: broad passive improvements that support the Harbinger/Shell plan.
Combat: modifiers tied more directly to weapon or sidearm performance.
Infusion: applies an elemental/status effect to compatible equipment.
Ability: adds a specific active/special move to a compatible weapon or sidearm.
Fragile (new): a consumable-style stone that breaks after losing durability. When it breaks it yields a Tarcore. Notable fragile stones now include Justiciar’s Stone and Gloombound Stone, which were converted to Fragile with increased passive effects and new break effects, and were added alongside the new Egon’s Stone.
The point is modularity: the same Shell can become a different build by changing the melee weapon, sidearm, compatible stones and the status effect you are trying to trigger.
What the Week 1 Update added
| Stone | What it does |
|---|---|
| Fragile Tarstones | Break after losing durability; drop a Tarcore on break; not unique, several per playthrough |
| Glimpse Stone | Wears down as you defeat enemies, then breaks into Glimpses |
| Egon’s Stone | Revives at a dungeon entrance on death inside a dungeon; when it breaks it prevents Gloom loss for that death |
| Fragile Justiciar’s / Gloombound | Converted to Fragile with stronger passive effects and on-break effects; existing copies converted |
Egon’s Stone status (September): two hotfixes repaired it after launch. The September 15 patch fixed dungeons failing to load after using the stone and closed a Gloom exploit around it; the September 25 patch fixed the stone removing Gloom dropped in the open world and took another pass at dungeon loading. If you shelved Egon’s Stone because dungeons would not open, it behaves as described above on the current build.
Certain enemies now drop fragile stones, several dungeons reward them, and Merrick sells them as his stock expands. He also sells Tarcores and Mether’s Severance (the Shell respec item) — more on that in the Glimpse guide.
Compatibility matters
Not every Tarstone fits every weapon. If a build guide says “use this stone” but it does not light up as compatible with your current weapon/sidearm, the guide may be describing a different equipment pair or an old patch interaction.
Full-release build testing repeatedly shows the best setups coming from one coherent interaction, not from stacking the four highest-looking numbers. Axatana’s Week 1 Update change makes this concrete: its weapon ability now grants invulnerability frames and inflicts Fragile stacks, so pairing it with a Fragile-intensive build is a genuine interaction now, not a guess.
Tarstone XP
Equipped Tarstones gain experience while you kill enemies. Current Tarforge guides report that the stone needs to be slotted on equipment you actually have equipped for the XP loop to work.
You do not need to activate an effect on every kill just to earn XP.
Tempering is a separate unlock
The Tarforge in Marrow Keep does not expose every function immediately. Current launch routes tie Tarstone tempering to the Etching Needles (or an alternate aggressive shortcut involving Franz that this site does not recommend as the default path).
See Tarstone Tempering for the upgrade route.
The upgrade economy changed with Week 1 Update
Two things that directly affect how you plan upgrades:
- Tarcores are no longer finite — all Tarstones can be upgraded in a single playthrough.
- Tarstones now yield more Tarcores when broken — and if your save already has leveled-up Tarstones, a compensatory cache of Tarcores is placed in your inventory.
The old “level only the stones in your main build, resources are scarce” planning is obsolete. Level what you use, and don’t fear re-spending.
Balance Patch 1 history
The first balance post buffed several named stones (Parasitic, Grudge, Bulwark, Clerik’s, Squall), and Weltcap got another boost in Week 1 Update. Tarstone tier lists remain patch-sensitive — check the in-game description before spending upgrade resources.
Build Tarstones around the Shell loop
Examples from full-release testing:
- Eredrim: support Break/riposte frequency, Resolve generation and the weapon’s best stagger window. Riposte damage now scales with enemy health, so riposte-leaning setups get better in late game.
- Genessa: reinforce Phantom stacking, multi-hit attacks and safe summon pressure.
- Proxima: support Shock/Lightning interactions rather than generic damage alone.
The Shell should tell you what question the Tarstones need to answer.
Last verified: 2026-08-30.