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Sanctums: Puzzle Dungeons and Rewards
Which Sanctums need a partner, what a rusted key opens, why you should buy keys before you enter, and what pays out besides the chest.
The short version
- Some Sanctum puzzle dungeons need a party of at least two players, so you cannot clear every one alone.
- Buy keys and items before you go in: vendors inside a dungeon charge more for the same things.
- Difficulty tiers and key rooms open with keys such as rusted keys, and Nightmare key rooms need a legendary key.
- Completing or closing a Sanctum gives Lumin Amber, and clears also give experience, rare materials and chests that can hold Flux Crystals.
- In co-op, one player opening a chest also rewards nearby players in the session who have not opened it yet.
Sanctums are Aniimo's puzzle dungeons. Each is an instanced shrine where you solve a run of environmental puzzles and claim a chest at the end. They are tied to world progression, and they are one of the steadier sources of experience and materials in the game.
They also come with some friction. Some need a second player. Some rooms stay shut until you have the right key. Shopping in the wrong place costs you extra. This guide covers how Sanctums are built, how keys work, what you get for clearing them, and how to get in and out.
How a Sanctum works
Inside a Sanctum you cannot bring your whole roster. You are limited to twining with select Aniimo, and the puzzles are built around what those Aniimo can do. Work through the series of environmental puzzles and a chest waits at the end.
The format is not one fixed thing. Sanctums are built as cooperative dungeons that need teamwork, and they also come in solo, partner-required and timed variants. Which kind you get depends on the Sanctum, so check before you commit a session to it.
The partner requirement is real. Certain Sanctum puzzle dungeons have a minimum party size of two players, and the co-op ones are designed as challenges for two players using their Aniimo. If you mostly play alone, some Sanctums will stay closed to you until you find someone to bring.
Two
Minimum party size for certain Sanctums
Keys, tiers and where to buy them
Sanctum difficulty tiers and key rooms are unlocked with keys. Rusted keys are the common example. Nightmare key rooms are a step above: they need a legendary key, so a rusted key will not get you through that door.
The practical rule is simple. Stock up before you enter. Keys and items bought from vendors inside a dungeon cost more than the same things bought beforehand. The vendor inside is there for when you run short, not for your main shopping.
What a clear is worth
Completing a Sanctum puzzle dungeon awards experience points and yields rare materials. Completing or closing a Sanctum also rewards Lumin Amber. Lumin Amber is a collectible found across the open world through exploration, movement puzzles, minigames, time trials, temples and pick-ups, so Sanctums are one source among several rather than the only one.
Sanctum chests are also a source of Flux Crystals, a currency you get from other reward sources too. How Flux Crystals are used is not settled. They act as evolution stones that stand in for missing elemental stones or evolution materials during resonance star-up. They act as a universal elemental resource that covers whatever element a material requirement asks for. They can also be exchanged for other items.
Co-op has a useful rule for chests. When one player opens a treasure chest, including inside a Sanctum, the other nearby players in the session who have not opened it yet are rewarded too. Nobody has to race for the loot.
If the partner-only Sanctums are out of reach for you, you are not locked out of their loot for good. Rewards from co-op Sanctums can be acquired through other methods.
Eggs inside a Sanctum
Some eggs sit inside Sanctums, and those eggs, like eggs at higher difficulties, are guarded by hostile Umbra Aniimo or bosses. Expect a fight before you collect.
Taking one starts with digging it out. Press the F key to unearth it, or interact with the nest and keep pressing the on-screen dig button. The full egg hunt has its own guide on this site; inside a Sanctum, it works the same way.
Getting in, out and around
In the Operation: Egg Heist mode, you enter the Sanctum through the blue gate. When you are done, the purple gate takes you out of the Sanctum and back to the outdoor area near the boats.
Sanctum dungeons also work as fast travel points. Once you know where they are, they double as ways to get around the map, which makes them worth finding even before you are ready to clear one.
Where to start
Buy your keys outside, bring a partner for the two-player Sanctums, and save legendary keys for Nightmare rooms. Treat each Sanctum you find as a fast travel point too. If you play solo, look for the co-op rewards through other routes rather than waiting on a group.
Most of this page was re-checked against the released game on 2 October 2026. The rest has not been re-confirmed since release.