Shadow Crystal

Shadow Crystal is a mysterious key item obtained from defeating a bonus boss in Deltarune (Jevil in Chapter 1 and Spamton NEO in Chapter 2). They can be given to Seam, who explains that the crystals may be found with powerful enemies, and that said crystals are invisible but still cast a shadow.
Prior to version v1.07, the one collected from Jevil did not appear in the party's inventory and was instead discovered by Seam upon talking to them in Castle Town during Chapter 2.
Upon collecting the second one from Spamton and bringing it to Seam, they explain that the next foe that carries one of these may be completely unbeatable without an item known as the Shadow Mantle, which they intend to give to the party, but cannot find.
If the party has defeated Jevil in any save file (but did not in the current save file, or otherwise lost Jevil's reward item), they can find the first Shadow Crystal (and the Devilsknife or Jevilstail) by inspecting the hole in the cliff to the left of Castle Town. If the party gives the second Shadow Crystal to Seam but have not given them the first, Seam hints at this, mentioning that the party did not collect the crystal from Jevil but that if they ever have defeated him then it will show up nearby.
== Glass ==
The Glass is the Light World form of the Shadow Crystal, separate from the Ball of Junk. It cannot be dropped, as "the thought of discarding it felt very wrong." Using the Glass makes Kris see through it, either seeing Susie glaring at them if she is following, otherwise seeing through their hand.
== Flavor Text ==
Using the Shadow Crystal/Glass makes Kris see something related to the theme of that chapter's Dark World, or some kind of illusion in the Light World. This effect quickly passes and is not repeatable.
=== Shadow Crystal ===
* You held the crystal up to your eye.
** For some strange reason, for just a brief moment... [First use]
*** You thought you saw toys strewn on the floor. [Card Kingdom]
*** You thought you saw the computer lab. [Cyber World]
*** ...but, it must've just been your imagination. [Follow-up, either]
** ... but nothing happened. [Second use, or Castle Town]
* It doesn't seem very useful. [Subsequent uses]
=== Glass ===
* You looked through the glass.
** For some strange reason, for just a brief moment... [First use]
*** You thought you saw through your hand. [Alone]
*** You thought you saw Susie glaring at you, coldly... [Followed by Susie]
**** But when you moved the glass away,
**** You see her looking at you, smiling and making a rude gesture.
** ... but nothing happened. [Second use]
* It doesn't seem very useful. [Subsequent uses]
* (You didn't quite understand why...) [Attempting to drop]
** (But, the thought of discarding it felt very wrong.)
== Trivia ==
* An unused item called the Pure Crystal exists. The Pure Crystal's item description, "the shadow purified by the cat", suggests it is a Shadow Crystal that has been "purified" by Seam.
* Prior to version v1.06 of Deltarune Chapter 2, the Glass did not appear in the Light World inventory due to a glitch.
* v1.19 introduced an indicator of attained Shadow Crystals per save file and chapter to the chapter select screen.
== References ==
ru:Теневой кристалл
zh:暗影水晶