The Clockwork Shardstone is an Ability Tarstone that keeps a chainsaw spinning along your weapon while it drains Resolve, and it sits behind one of the few pickups in Mortal Shell 2 that the map never points you toward. No boss drops it, and the dungeon that holds it is sealed shut until you fire a catapult on the other side of the region.
Quick answer: Pick up the Makeshift Projectile below the Outskirts of Mammon Beacon, load it into the catapult east of the beacon statue to blast open the Alchemist’s Workshop entrance near Castigator’s Keep, then walk through the bookshelf inside, pull the lever, ride the lift down, and open the chest in the final room.
What the Clockwork Shardstone does and which weapon takes it
The Shardstone is an Ability-type Tarstone, so it adds an action rather than a passive stat. Slot it in and it consumes Resolve continuously to hold your weapon out with its chainsaw running at full speed, and every attack lands with that chainsaw biting. It only fits one weapon in the game, the Clockwork Scythe, which is the reward for beating Sariel, the Endless in the Chamber of Becoming dungeon. Without that scythe, the stone has nowhere to go.
| Level | Effect |
|---|---|
| 1 | Consume Resolve over time to hold your weapon before you with its chainsaw spinning at full speed |
| 2 | Each chainsaw spin deals 12% of the weapon base damage |
| 3 | Each chainsaw spin deals 15 Stagger Damage |
| 4 | Each chainsaw spin deals 20% of the weapon base damage |
Because the cost is a steady Resolve drain instead of a single spend, the stone rewards staying in contact with enemies and punishes long stretches of holding back.
Open the Alchemist’s Workshop with the Makeshift Projectile
The dungeon door does not exist until you fire the catapult, so do this half first. Hunting for the entrance beforehand is wasted travel.
Note: the Workshop occupies the western area that connects the Lonesome Spire with the main Castigator’s Keep building, so if you are wandering the eastern half of the keep you are on the wrong side.
Clockwork Shardstone location inside the dungeon
The Workshop hides its own path once you are inside. The stone is not a boss drop, so nothing will be handed to you automatically at the end.
Why the dungeon entrance may not appear
Nearly every failed run comes down to a small number of skipped beats, and each one has an exact cause.
| Symptom | Cause |
|---|---|
| No door near Castigator’s Keep | The catapult has not been fired; only the Makeshift Projectile opens the entrance |
| Projectile picked up but nothing changed | It was never loaded into the catapult east of the beacon statue |
| Dungeon appears to end early | The bookshelf was treated as a solid wall instead of a passage |
| Lift will not move | The lever in the secret room has not been pulled |
| Final enemy died, no Tarstone | The Shell Thief is not the source; the chest in that room has to be opened |
How to upgrade the Clockwork Shardstone at the Tarforge
Levelling happens at the Tarforge in Marrow Keep, but only after Franz has the Etching Needle. That quest item expands what the Tarforge can do, and it sits in a chest just before the Magdalena, the Lady of the Woods fight. When you spot Ruk past the bridge, drop through the opening and turn right before the tunnel to reach a small alcove with a bone chest holding the needle.
After handing it over, equip the Shardstone and kill enemies to fill its experience bar. Once the bar is full, return to Franz and pay Coin to push it to the next level. Repeat that cycle through all four ranks to reach the 20% base-damage spin.
Since the Clockwork Scythe also accepts the Scholar’s Wormstone, and Ability stones can be equipped two at a time, the two of them stack into about as dedicated a setup as any weapon gets in Mortal Shell 2. Just keep an eye on Resolve, because the chainsaw stops the moment the meter runs dry.
