How To Get Arcane Keystones In Genshin Impact: Complete Location & Puzzle Guide

To obtain Arcane Keystones in Genshin Impact, travel to the Faded Castle in the Nostoi Region (Fontaine) during or after the "Canticles of Harmony" World Quest line. You must harness the Symphony skill to capture flying Lost Grimoires, place them into glowing bookshelved mechanisms, and solve sound-resonance puzzles across the upper, middle, and lower exhibition halls of the castle. Collecting these keystones unlocks high-tier chests, hidden chambers, and essential progress toward 100% exploration of the Sea of Bygone Eras.

Pre-Quest Prerequisites & Symphony Power Setup

Before attempting to gather Arcane Keystones, your account must meet specific progression benchmarks and quest triggers in the Fontaine / Nostoi region. These quest items are embedded directly within the environment mechanics of the Faded Castle, requiring a specialized interaction skill unlocked early in the version 4.6 map expansion.

• Adventure Rank & Progression Requirements:
  
  
  • Minimum Adventure Rank: AR 20 (AR 40 recommended for optimal combat efficiency against level 90+ opponents).
  • Archon Quest Prerequisite: Complete Archon Quest Prologue: Act III "Song of the Dragon and Freedom" to unlock the automatically activated Teleport Waypoint in Petrichor.
  • Required World Quest: "Canticles of Harmony" (specifically Act I: "The Shadow Over Petrichor" and "Petals of Sailcloth Driven by the Wind").
• Essential Mechanics & Combat Preparation:
  
  
  • Symphony Power (T-Button / Special Interaction Skill): Replaces your standard gadget button inside Nostoi and Remurian zones. A quick press emits a sound wave that stops moving objects (like floating books) or triggers musical devices, while holding the skill casts an ongoing acoustic resonance field.
  • Shield-Breaking Party Members: High-density Geo characters (Zhongli, Navia, Itto) or Blunt-damage dealers (Claymore users) are mandatory to efficiently break the Geo shields of Praetorian Golems guarding keystones.
  • Hydro Mobility: Characters like Neuvillette, Yelan, or Furina significantly streamline navigation through the underwater and vertical geometry of the Faded Castle.
• Estimated Investment Benchmark:
  
  
  • Completion Time: 30 to 45 minutes once the preliminary Petrichor dialogue is finished.
  • Total Yield: Multiple Arcane Keystones/Lost Page keys, 3 Exquisite Chests, 2 Precious Chests, 1 Luxurious Chest, and 30 Primogems from spatial rewards.

Step-by-Step Execution to Obtain Every Arcane Keystone

Step 1: Initiate the Canticles of Harmony Questline in Petrichor

Begin your journey by teleporting to Petrichor village on Nostoi Island. Walk toward the marked quest location in town to trigger the cutscene with the talking cat named Osse and the researcher Est.

1. Follow Osse through the ruined stairs into the subterranean entrance leading under the island.
2. Advance through the cave until you discover the hidden portal opening into the Faded Castle: Middle Level.
3. Activate the nearby Teleport Waypoint to bind your spawn point and unlock the Symphony Power interaction icon on your action bar.

Warning: Attempting to explore the Faded Castle without starting "Canticles of Harmony" will prevent Lost Grimoires from floating and keep the glowing bookshelf mechanisms completely uninteractable.

Step 2: Navigate to the Faded Castle Middle Level Library

From the Middle Level Teleport Waypoint, head east across the stone bridge toward the multi-tiered library chamber. You will observe glowing, autonomous books (Lost Grimoires) fluttering around the balcony walkways.

1. Approach the main corridor where the first flying Lost Grimoire loops along a set flight path.
2. Align your character directly in front of the floating book's trajectory.
3. Tap your Symphony skill button (or press "T" on PC) precisely as the book passes through your golden radius. This stuns the book, causing it to hover motionless in mid-air.
4. Interact with the stunned book to collect the "Lost Grimoire" into your quest inventory.

Step 3: Unseal Bookshelves to Collect Arcane Keystones

With a Lost Grimoire in hand, inspect the nearby walls to locate glowing, unsealed bookcases embedded with acoustic locks.

1. Walk up to the glowing bookshelf on the lower balcony level.
2. Select the "Put In" prompt and submit one Lost Grimoire from your inventory.
3. Hold down your Symphony skill button near the loaded bookshelf. This forces the cabinet to dissolve using acoustic resonance, opening a passage into a hidden room behind the wall.
4. Defeat the Praetorian Golem waiting inside the secret room using Blunt or Geo attacks to strip its Geo shield.
5. Open the revealed chest and collect the Arcane Keystone resting on the central altar or bookshelf pedestal.

Pro-Tip: If a flying Lost Grimoire moves out of reach, hold down the Symphony skill button while standing under its flight path. The extended acoustic wave drags the book down toward your position, allowing easy capture without climbing walls.

Step 4: Solve the Lower Level Autoharmonic Chime Puzzles

Ascend or descend via the central lift platforms to reach the Faded Castle: Lower Level and Exhibition Hall to locate the remaining keystones.

1. Teleport to the Faded Castle: Lower Level Waypoint and move south toward the giant musical organ mechanism.
2. Locate the two fluttering Lost Grimoires patrolling the upper platforms above the organ.
3. Freeze both Grimoires using your Symphony skill and collect them sequentially.
4. Insert the first Grimoire into the northern bookshelf to open the barrier hiding an Arcane Keystone and an Exquisite Chest.
5. Insert the second Grimoire into the southern bookshelf, hold down the Symphony skill to push the hidden bookshelf backward, and reveal an inner corridor leading to a Praetorian Golem boss encounter.
6. Defeat the elite Golem to unlock the final Arcane Keystone and a Luxurious Chest containing Remurian artifacts.

Faded Castle Arcane Keystone Locations & Interaction Mechanics

Exploration Pitfalls & Common Puzzle Fixes

Lost Grimoire Escapes or Glitches Mid-Air

• Root Cause: Activating your Symphony skill too early or missing the collision box causes the book to speed up and fly beyond the platform ledge.
• Actionable Fix: Teleport to the nearest Waypoint outside the Faded Castle, wait 10 seconds for the entity state to clear, and return. The Lost Grimoire will reset to its original, slow-moving flight loop.

Bookshelf Refuses to Dissolve After Inserting Grimoire

• Root Cause: Simply placing the book into the shelf only unlocks the mechanism; it does not trigger the physical transformation without active Symphony resonance.
• Actionable Fix: Stand directly against the loaded bookshelf, hold the Symphony skill button for a full 1.5 seconds until the sound gauge fills completely, and release it to slide the secret wall back.

Locked Gate Barriers Won't Lower in the Exhibition Hall

• Root Cause: You are attempting to interact with the master door mechanism before obtaining all required regional Arcane Keystones.
• Actionable Fix: Open your Inventory tab under "Quest Items" and verify your Keystone count. If you are missing one, check the Middle Level Upper Gallery balcony, which is frequently overlooked due to vertical geometry occlusion.

Praetorian Golem Geo Shield Takes Zero Damage

• Root Cause: Standard Physical or Elemental Attacks (Anemo, Cryo, Pyro, Electro) deal negligible poise/shield damage to Remurian Golem armor.
• Actionable Fix: Switch to a Geo character (Navia, Zhongli, Ningguang) or a Claymore wielder (Diluc, Noelle, Eula) and execute Heavy/Plunging attacks to strip the shield meter in 2-3 hits.

Frequently Asked Questions

Can I get Arcane Keystones without starting the Canticles of Harmony quest?

No. While you can physically walk into Petrichor, the lower entrances to the Faded Castle remain sealed, and the Symphony skill interface will not be available on your screen until you trigger the quest dialogue with Est and Osse.

Do Lost Grimoires or Arcane Keystones respawn after the daily server reset?

No, Arcane Keystones and Lost Grimoires are non-respawning, finite quest items. Once collected and used to unseal the Faded Castle's hidden rooms, they are permanently removed from your active quest inventory.

What are Arcane Keystones used for in Genshin Impact?

Arcane Keystones serve as key items required to bypass sealed energy barriers and acoustic locks within the Faded Castle. Using them allows access to secret treasure vaults containing Luxurious Chests, Hydroculi, and progression items for the Sea of Bygone Eras.

Why does my Symphony skill button disappear while inside the Faded Castle?

The Symphony skill button is bound to the Nostoi Region environment. If you step into an out-of-bounds cave section, engage in specific instance triggers, or enter combat where environmental interactions are restricted, the icon will temporarily revert to your standard equipped gadget.

Master the Echoes of Remuria

Now that you have collected every Arcane Keystone and unlocked the secret vaults of the Faded Castle, continue your journey deeper into the sunken realm of Remuria. Dive into the Sea of Bygone Eras to complete the remaining acts of the Canticles of Harmony and maximize your Fontaine exploration achievements!