Shadow Crystal boss
If you can defeat more strong adversaries, you may find more Shadow Crystals.
Try your best! It may be tough, but I'm sure it will be worth it!Seam, Chapter 2
Shadow Crystal bosses[note 2] are a type of boss in Deltarune. They are optional, often hidden encounters that are more difficult than the rest of the Chapter, but reward the party with powerful exclusive equipment when completed, as well as an instance of the unique Shadow Crystal item.
Each Chapter in Deltarune contains one Shadow Crystal boss. Although their battles are optional, encountering the character itself may not be; all but one Shadow Crystal boss (Jevil) are required to interact with as part of their respective Chapter's story. Reaching their battle requires following a sidequest that involves backtracking to previously visited areas. Despite being optional, clearing their encounters reveals hidden context, unstated elements, or other unique insights into the story of Deltarune.
Seam, the shopkeeper in charge of managing the party's Shadow Crystals, seems to be aware of the Shadow Crystal bosses, hinting at future encounters and warning the group of their power.[6][7][8]
Their battles are scripted, going through a predetermined order of attacks and dialogue until a specific threshold is met towards the end of the battle. Upon meeting said threshold, the boss uses a "final" attack that is longer, harder and more visually elaborate, ending in a "fakeout" attack that appears undodgeable but ends before hitting the SOUL. After defeating a Shadow Crystal boss, either through ACTing or FIGHTing, they reward the party with a unique piece of gear; while all of them provide a weapon, Jevil and Spamton NEO instead provide a piece of armor if defeated peacefully. Additionally, the party also receives the boss's Shadow Crystal, a unique Key Item of yet-unknown use.
Besides their gameplay mechanics, Shadow Crystal bosses share several thematic and narrative elements, despite being otherwise unrelated:
- They have dialogue sounds, but no dialogue portraits.
- Their battle theme contains a shared leitmotif.
- Their battle narration includes the specific phrase "The air crackles with freedom.", or a variation of it.
- They directly mention the Knight in dialogue.[9][10][11][12]
- They foreshadow characters or events from future Chapters.[13][14][15][16]
- There are allusions to them having been contacted by an unknown individual in the past. It is unknown if they were all in contact with the same individual.[17][18][19]
The Knight, Chapter 3's Shadow Crystal boss, serves as an exception to a majority of these trends. Encountering it is required to finish Chapter 3, although losing to it still progresses the plot. As its complex patterns and high damage will likely end the encounter in a few turns, the fact that the fight can be won can be considered the "secret". Various thematic elements associated with Shadow Crystal bosses are instead relegated to the Sword Route, an extensive sidequest that ultimately rewards Kris with the Shadow Mantle, an item that reduces the difficulty of the Knight's boss fight.
This list is sorted in Chapter order.
The former court jester of Card Castle, and Chapter 1's Shadow Crystal boss. He went mad after meeting a "strange someone", which led him to start seeing the world as a game. Thus, he was imprisoned at the ?????? floor. The party can assemble the Door Key to his cell to enter it and fight him.
Reward: Jevilstail (ACTing) or Devilsknife (FIGHTing)
The upgraded form of Spamton, a disgraced spambot salesman found in Chapter 2's Cyber City as a miniboss. After completing his mandatory encounter peacefully, he gives Kris a series of instructions to smuggle him into the basement of Queen's Mansion. Once there, he combines with a machine found in the basement to become Spamton NEO, and attempts to utilize its power to steal Kris's SOUL.
On the Weird Route, he is instead the Chapter's mandatory final boss, having snuck into Queen's Mansion as a result of Kris and Noelle's actions. He still yields a Shadow Crystal upon defeat.
Reward: Dealmaker (ACTing) or PuppetScarf (FIGHTing)
The Roaring Knight is the main antagonist of Deltarune, a mysterious being responsible for the creation of the Dark Fountains. As described above, the Knight serves as the highly unconventional Shadow Crystal boss of Chapter 3, attacking Tenna after his defeat and taking his place as the Chapter's real final boss. Its fight is extremely difficult, although it can be made easier by obtaining the Shadow Mantle earlier in the Chapter. Either winning or losing the fight is a valid end to the Chapter; winning the battle causes the Knight to retaliate and knock the party out anyway.
Reward: BlackShard
The Old Man is a Darkner created from mementos of his Lightner counterpart, Gerson. Making his appearance in Chapter 4, he guides the party and serves as a mentor to Susie, in addition to acting as a shopkeeper. The party can embark on a sidequest to reveal a hidden room in his Study. Inside, the Old Man, as the Hammer of Justice, offers to fight Susie one-on-one in exchange for an expensive weapon.
Reward: JusticeAxe
- ↑ Ura (裏) is Japanese for secret or hidden.
- ↑ Shadow Crystal boss is an unofficial name. Per community vote on June 12, 2025, this wiki uses this name, as opposed to any of their other common names.
- ↑
Jevilishly difficult hidden bosses.
— DELTARUNE on Steam (September 17, 2021.) store.steampowered.com. - ↑
The hidden boss becomes subtly more difficult when angry.
— @UnderTale on Twitter, September 30, 2021. - ↑ The filename of Hammer of Justice is
ch4_extra_boss. - ↑
KID! I'M BUSY BECOMING [God]. GO PLAY [Minecrap] OR SOMETHING!
— Spamton, Weird Route, Chapter 2
IT'S NOT MY JOB TO BE SOME KIDS' [Extra Boss]! - 1 2 gml_GlobalScript_scr_save script, lines 16–28, Chapter 3
- ↑
If you can defeat more strong adversaries, you may find more Shadow Crystals.
— Seam, if given Jevil's Shadow Crystal, Chapter 2
Try your best! It may be tough, but I'm sure it will be worth it! - ↑
You have collected 2 Shadow Crystals.
— Seam, after being given a second Shadow Crystal, Chapter 2
But don't let down your guard. I feel your next opponent may be... hm.
In reality, it may be impossible to win.
... Unless you use the power of the Shadow Mantle.
Here, it may look like an old scrap of cloth, but...
... eh?
I can't find it. Did someone... take it...?
Hahaha! Well now, there goes your one chance of victory! - ↑
It's strange. By all reasonable means, the strength of your next opponent...
— Seam, after being given a third Shadow Crystal, Chapter 4
Should be enough to already ring the bell on your defeat.
But, for some reason... I can't help but think you may win.
What is this feeling? ... Hope? Hahaha! Whatever it is, it's quite funny! - ↑
YOU'RE FAST, FAST, STRONG, STRONG.
— Jevil upon his defeat via FIGHTing, Chapter 1
BUT THERE ARE YET FASTER, YET STRONGER.
THE HAND OF THE KNIGHT IS DRIFTING FORWARD. - ↑
FROM NOW, A NIGHTMARE WILL AWAKEN IN YOUR HEARTS.
— Jevil upon his defeat via Ralsei's Pacify spell, Chapter 1
IN THE SHADOW OF THE KNIGHT'S HAND... - ↑
SPEAKING OF [[Communion]]
— Spamton, "Knight", Chapter 2
KRIS, DID YOU KNOW THAT THE KNIGHT... - ↑
A figure with a sword flew in that door up there.
— Old Man, Chapter 4 - ↑
SOON, THE "QUEEN" RETURNS, AND HELL'S ROAR BUBBLES FROM THE DEPTHS...
— Jevil upon his defeat via FIGHTing, Chapter 1 - ↑
WE DON'T NEED ANYONE ELSE!!! WE DON'T NEED [[Easels]] or [[CRTs]]!
— Spamton in his shop, Chapter 2
WE DON'T NEED ANY [[Man, Woman, or Child]] [[At Half Price]]!!
WE DON'T NEED [[MIKE]]!!!
... ... Mike...
KRIS!!! DON'T BELIEVE [[Anything You See On TV!]] THE MAN'S A CRIMINAL, I TELL YOU!! A CRIMINAL!! - ↑
Chapter 5, The Field of Pink and Gold.
— Hammer of Justice in battle, Chapter 4
The vast garden is charred in an inferno of jealousy. - ↑
TO [$!$!] ME OVER RIGHT AT THE [Good part]!? WHAT ARE YOU, A [Gameshow Host]!?
— Spamton NEO, Weird Route pre-battle, Chapter 2 - ↑
One day, he met a strange someone... and since then, he began to change.
— Seam about Jevil, Chapter 1
He started saying bizarre things that didn't completely make sense -
But didn't completely not make sense, either. - ↑
He started to get a little desperate.
— Orange Addison in Trash Zone, Chapter 2
I heard he started looking for any way to become more popular.
Somehow, he made the right phone call, and found someone.
Or, was he... found BY someone?
They must have been helping him, because suddenly,
He was on the phone all the time... - ↑
For some reason, I found this weird piece-a glass in my desk.
— Hammer of Justice post-boss fight, Chapter 4
Felt like someone really wanted me to use this thing.
But it didn't interest me, so you can take it.