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The Crystal Key is a mysterious item dropped by the High Alchemist miniboss in the Ancient Laboratory. Depending on the player's actions, it is used to open either the Dark Chest or the Coral Chest. Multiple Dark or Coral chests can be opened by going into a Parallel World to defeat another High Alchemist and get another Key.
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. The player 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.
In order for the Crystal Key to unlock the Coral Chest, the player 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 the player must kick the Music Machine to start the music. The Music Machine locations are as follows:
- On top of the Giant Tree next to the player's starting point.
- In the Snowy Wasteland, just before the Lake, atop the pillar. (Previously it was to the left of the wooden effigy on the island of the Lake.)
- 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.
For the first three music machines the key is presented, the player will receive this message:
The key listens...It's taking in the music.
Once the Crystal Key has listened to all four music boxes, the player will receive a new message:
The key has taken in the full songIt's ready.
At this point, the Key can be taken to the Coral Chest in the clouds above the Pyramid. When the Key is thrown at the Coral Chest, the player receives one final message:
The chest opens!But the key might have other stories to tell...
If the player has previously opened the Coral Chest, a random three spells from the above list will be dropped instead of all five.
In order for the Crystal Key to unlock the Dark Chest, the player 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.
The order the songs are played do not matter. Once the first song is played, the player receives the message:
The key begins to hum!Something is still missing...
Once both of the songs are played to the Crystal Key, the player receives 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, the player receives the message:
The glass key speaks!The chest listens
The Dark Chest will emit a large circle of Blood and the player is immediately rewarded with the following six "Spells To..." spells, which will unlock them for future runs. Additionally "Copy Trail" is unlocked for future runs, but is not a reward for first-time opening.
- Spells To Nukes
- Spells To Giga Sawblades
- Spells To Magic Missiles
- Spells To Death Crosses
- Spells To Black Holes
- Spells To Acid
- Copy Trail
If the player has 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 undestand these words, but I still see the Diamond in my mind's eye..."