Crystal Key

The Crystal Key is a mysterious item used to open a special type of chest, dropped by the High Alchemist in the Ancient Laboratory.

Depending on your actions, it is used to open either the Dark Chest or the Coral Chest. Multiple Dark chests can be opened by going into a Parallel World to defeat another High Alchemist and get another Key. Coral Chests spawn in parallel worlds, but only one key can be filled with music from the Music Machines, so only one Coral Chest can be opened per run.

Uses

In its initial state, the key will be described as voiceless. In this state, the key is completely useless and is unable to unlock either of the chests. You must first give the key a voice in one of two ways in order to use it to unlock the corresponding chest. Each chest contains a selection of unlockable spells that will start appearing in future spell shops and chests once the associated chest has been opened.

Coral Chest

The Coral Chest's resting place.

The Coral Chest can be found on the eastern side of the Eastern Cloudscape.

In order for the Crystal Key to unlock the Coral Chest, you must bring it to all four Music Machines of the world. The Key must be dropped or thrown on the ground near a Music Machine, and you must kick the Music Machine to start the music. The Music Machine locations are as follows:

On top of the Giant Tree next to your starting point.
In the Snowy Wasteland, just before the Lake, atop the pillar.
At the bottom the pond full of fish, on the right side of the Forest.
Far to the right of the Pyramid, resting on the sand.

Music Machines are not indestructible and can be destroyed, or may fall through the ground due to physics bugs. More music machines are present in the first Parallel World in each direction, but not beyond. (The Parallel World spawning Music Machines are not without their bugs either, particularly the pond one may have extra issues since the land generation is different and it can bug rather badly, either destroying or throwing it a distance away from spawn)

For the first three music machines the key is presented, you will receive this message:

The key listens...It's taking in the music.

Once the Crystal Key has listened to all four music boxes, you will receive a new message:

The key has taken in the full songIt's ready.

The music machines' songs can only be played to a single key per run, including New Game Plus cycles (so, if a partially charged key is destroyed, the quest cannot be completed).

When fully charged by all four songs, the Key can be taken to the Coral Chest in the clouds above the Pyramid. When the Key is thrown at the Coral Chest, you receive one final message:

The chest opens!But the key might have other stories to tell...

The chest will then emit a Circle of Water and drop the following five Spells, which will be permanently unlocked, allowing them to spawn from that point on.

Coral Chest Spells

Octuple Spell

Simultaneously cast 8 spells

Myriad Spell

Simultaneously casts as many spells as you have left uncast in your wand

Divide By 2

Casts the next spell 2 times, but with reduced damage

Divide By 3

Casts the next spell 3 times, but with reduced damage

Divide By 4

Casts the next spell 4 times, but with reduced damage

If you have previously opened the Coral Chest, a random three spells from the above list will be dropped instead of all five.

Dark Chest

The Dark Chest's resting place.

There is a hint book for this, named the Alchemist's Notebook, in the Overgrown Cavern.

In order for the Crystal Key to unlock the Dark Chest, you must play two magical songs to the Crystal Key while it is on the ground, one song with the Kantele notes and one song with the Huilu notes. The Note spells are the important thing; the instrument wands themselves are not required. It's not necessary to have the entire songs equipped on a wand at once; the songs can be played one note at a time or a few notes at a time by swapping notes in and out of the instruments.

Kantele

Huilu

{{Wand2|defaultWrap=1|tooltips=0|spells=KANTELE_G, KANTELE_DIS, KANTELE_G, KANTELE_E, KANTELE_A|spellsCast=1|castDelay=0.17|rechargeTime=0.48|manaMax=900|manaCharge=700|capacity=5|spread=-2.0|speed=1.00|Shuffle=0|wandName=|wandPic=Kantele (Wand).png|wandPicId=0821}}

Tinker

Visit the Wand Simulator site to view & edit this wand

Shuffle

No

Spells/Cast

1

Cast delay

0.17s

Rechrg. Time

0.48s

Mana max

900

Mana chg. Spd

700

Capacity

5

Spread

-2°

Speed

1.00×

{{Wand2|defaultWrap=1|tooltips=0|spells=OCARINA_E, OCARINA_C, OCARINA_B, OCARINA_GSHARP, OCARINA_F|spellsCast=1|castDelay=0.17|rechargeTime=0.48|manaMax=900|manaCharge=700|capacity=5|spread=-2.0|speed=1.00|Shuffle=0|wandName=|wandPic=Huilu (Wand).png|wandPicId=0821}}

Tinker

Visit the Wand Simulator site to view & edit this wand

Shuffle

No

Spells/Cast

1

Cast delay

0.17s

Rechrg. Time

0.48s

Mana max

900

Mana chg. Spd

700

Capacity

5

Spread

-2°

Speed

1.00×

The order the songs are played do not matter. Once the first song is played, you receive the message:

The key begins to hum!Something is still missing...

Once both of the songs are played to the Crystal Key, you receive the message:

The key begins to whisper!"I can give you so much in exchange for..."

The key can now be brought to the Dark Chest in The Work (Hell). When the Key is thrown towards the chest, you receive the message:

The glass key speaks!The chest listens

The Dark Chest will emit a large circle of Blood and you are immediately rewarded with the following six "Spells To..." spells, which will unlock them, allowing them to be encountered from that point on. Additionally Copy Trail is also unlocked, even though it can't be gained from the chest.

Dark Chest Spells - Unlocks

Copy Trail

Makes a projectile leave a trail of copies of itself

Spells To Acid

Transforms every projectile currently in the air into a pool of acid

Spells To Black Holes

Transforms every projectile currently in the air into a black hole

Spells To Death Crosses

Transforms every projectile currently in the air into a death cross

Spells To Magic Missiles

Transforms every projectile currently in the air into a magic missile

Spells To Nukes

Transforms every projectile currently in the air into a nuke, not a good idea

Spells To Giga Sawblades

Transforms every projectile currently in the air into a giant sawblade

Dark Chest Spells - Drops

Spells To Acid

Transforms every projectile currently in the air into a pool of acid

Spells To Black Holes

Transforms every projectile currently in the air into a black hole

Spells To Death Crosses

Transforms every projectile currently in the air into a death cross

Spells To Magic Missiles

Transforms every projectile currently in the air into a magic missile

Spells To Nukes

Transforms every projectile currently in the air into a nuke, not a good idea

Spells To Giga Sawblades

Transforms every projectile currently in the air into a giant sawblade

If you have previously unlocked the Dark Chest, a random three spells from the above list will be dropped instead.

Along with the spells, the chest will also spawn a book, reading:

Book of the Jewel

"In my dream I saw a great Diamond...

It invited me within, offering me Grand Treasures.

This it said to me:

'If you wish to follow the Path I show you here, you must bring me one of these Two:

A terrible Curse of Avarice, or the most Singular being in this realm.'

I do not fully understand these words, but I still see the Diamond in my mind's eye..."

Trivia

The Coral Chest can still be opened after triggering the Pure Ending.
Previously, the "Lake" Music Machine used to be found to the left of the wooden effigy on the lake Island.