Genshin Impact Once, the Sacred Seat of Judgement quest guide

Once, the Sacred Seat of Judgement is a sub-quest under In Search of a Hidden Heart in Genshin Impact. To progress through the Chronicler of the Crumbling City quests, you must complete all five sub-quests under the In Search of a Hidden Heart quest.

Like all major world quests, Chronicler of the Crumbling City is filled with challenges and puzzles, especially the Once, the Sacred Seat of Judgement quest. It involves clearing out a pool of lava, collecting Coagulation Pearls using Yumkasaur while avoiding an instant-death layer, and solving several puzzles that may confuse Genshin Impact players.

Follow this guide to learn how to complete Once, the Sacred Seat of Judgement in Genshin Impact.

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Genshin Impact Once, the Sacred Seat of Judgement quest walkthrough

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Go to the Chamber of Deliberation to obtain the permit

Save the Secret Source Servant (Image via HoYoverse)

In Once, the Sacred Seat of Judgement, you must travel to the Chamber of Deliberation to obtain the permit required to enter the Heart of the Ancient Sacred Mountain.

The Chamber of Deliberation is located just north of the big Secret Source Servant who gave you the In Search of a Hidden Heart quest. There will be a large pool of liquid phlogiston, which should also be visible on the map.

Drop down to the pool, where you will spot a small Secret Source Servant being attacked by rifthounds. Defeat all the rifthounds, and as a token of gratitude, the Secret Source Servant will remove the liquid phlogiston.

Use Yumkasaur's ability to take the Coagulation Pearl at the bottom of the pool and fire it at the pedestal above the door to open the entrance to the Chamber of Deliberation.

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Activate the Purification Device

Entrance to the Chamber of Deliberation (Image via HoYoverse)

After entering the Chamber of Deliberation and speaking with Awanyu (the Secret Source Servant who you saved earlier), you will be tasked with activating the purification device to eliminate the rifthounds attacking the chamber.

Fire the pearl at the pedestal (Image via HoYoverse)

Just next to the Chamber of Deliberation is a teleport point, beside which is a Yumkasaur Spiritsconce. Turn into a Yumkasaur, take the Coagulation Pearl, and shoot it at the pedestal being attacked by rifthounds. This will activate the purification device and spawn a phlogiston barrier. Anything that touches the barrier, including you, will instantly die, which is why you must remain cautious.

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Raise the Phlogiston Barrier

Go to the next level (Image via HoYoverse)

Now, use Yumkasaur's ability to reach the platform on the left. There will be another Coagulation Pearl and a pedestal. Fire the pearl at the pedestal to raise the phlogiston barrier. Then, return to the pedestal you just activated to find an exquisite chest.

After looting the chest, use Yumkasaur's ability again to reach the top of the platform. There, you will find a group of four Secret Source Servants trapped inside a room. Use Yumkasaur's ability to activate the grappling hook and free them.

Free the Secret Source Servants (Image via HoYoverse)

Follow the Secret Source Automatons. Along the way, you must use Flamegranates to destroy rocks and clear a path for yourself.

Defeat slimes here (Image via HoYoverse)

Two Secret Source Servants will get distracted by groups of slimes. Defeat them to help the servants get back to work.

Second Coagulation Pearl (Image via HoYoverse)

Follow them to the very end, where you will find the room they were previously locked in. Inside, there is a Coagulation Pearl. Pick it up and shoot it at the pedestal in front of you.

Path to the next Coagulation Pearl (Image via HoYoverse)

There is another pedestal next to the one you just activated. It will now reveal the path to the next Coagulation Pearl. Follow the path and destroy any walls in your way. You will quickly find the Coagulation Pearl, but you will not be able to leave with it immediately.

Take the pearl through the cage (Image via HoYoverse)

Instead, leave the pearl there and walk to the room that contains a Pyroculus. From that location, you can collect the Coagulation Pearl through the cage.

Carry the pearl and walk on phlogiston (Image via HoYoverse)

From there, head down to the lake of phlogiston, where you will find a Secret Source Dragon. Near the lake, there is a Coagulation Pearl. Picking it up will allow you to walk on the liquid phlogiston. Cross to the other side of the lake and exit to find the pedestal for the third and final Coagulation Pearl.

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Receive the permit receptacle

Receive the permit receptacle (Image via HoYoverse)

After firing the third pearl at the pedestal, the phlogiston barrier will rise and reveal the permit on the head of the dragon statue. Go and pick up the permit receptacle.

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Watch out for the Phlogiston Barrier as it sweeps down

Carefully glide down (Image via HoYoverse)

As soon as you collect the permit receptacle, a group of rifthounds will enter and start attacking the pedestals. This will cause the phlogiston barrier to initiate a cleansing scan.

You must carefully glide down and avoid touching the phlogiston barrier, or you will die instantly and have to restart from the top.

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Activate the permit

Going to the top (Image via HoYoverse)

After the scan is complete, go to the centre of the Chamber of Deliberation to activate an elevator. Take the elevator to the very top to witness a beautiful cutscene showcasing the Ancient Sacred Mountain.

Take this elevator (Image via HoYoverse)

After a long dialogue sequence, you will receive the Permit to the Sacred Heart, along with two Luxurious Chests. This marks the end of Once, the Sacred Seat of Judgement quest in Genshin Impact.