You’ve befriended Ralsei, put up with Susie’s chalk eating habits, and fought your way through hordes of quirky enemies. But you’ve heard whispers, haven’t you? Rumors of powerful, hidden enemies lurking just off the beaten path. You’re looking for a real challenge, the kind of fight that makes you a legend. These are the Deltarune secret bosses, and they are the toughest fights in the game.
What Is on Our Deltarune Secret Boss Guide?
This guide will walk you through everything you need to know to find and defeat every single Deltarune secret boss from Chapter 1 to Chapter 4. We’ll cover the tricky puzzles, the epic battles, and the awesome loot you get for winning. Get ready to prove your determination!
What Are the Deltarune Secret Bosses?
Each chapter of Deltarune has a secret boss tucked away, hidden behind puzzles and quests that you could easily miss. These aren’t your average enemies. They are super powered beings that break the rules of combat and offer a massive spike in difficulty.
Why bother hunting them down? Two reasons: rewards and lore. First, you get some of the best gear in the game, which can totally change how you play. Second, each boss gives you a mysterious Shadow Crystal. We don’t know what these are for yet, but they’re clearly super important. Plus, these fights are connected to the deepest secrets of Deltarune’s story.
Chapter 1 Deltarune Secret Boss: Jevil, the Jester of Chaos
Your first taste of a true Deltarune secret boss is the chaotic jester, Jevil. This guy is a whirlwind of craziness, and his fight is a frantic bullet hell ballet that will push your dodging skills to the limit.
Finding Jevil: The Three Part Key Quest
To face Jevil, you first need to free him from his prison. He’s locked away in a cell on a secret floor of Card Castle. After escaping the dungeon, take the main elevator to the first floor, then find another elevator in the southeast. Choose the “??????” floor option to find Jevil’s cell. Talk to him, and he’ll tell you to find the key to his freedom, kicking off the quest.
The key is broken into three pieces scattered across the world.
- Broken Key A: Jevil gives you a clue: “The old shopkeeper knows a secret.” Go back to Seam’s shop and ask him about the “Strange Prisoner.” He’ll tell you about his history with Jevil and hand over the first piece.
- Broken Key B: Seam gives you the next clue: “walk where the stars don’t shine.” This points to the Forest. On the screen with the spiraling Paper Dancers, go to the bottom left corner. There’s an invisible path leading south off the walkway. Follow it to find a chest with the second key piece. This is the game teaching you to look for hidden paths!
- Broken Key C: The final piece is in the Field, past the Bake Sale area. You’ll find a combination puzzle on a wall. The solution is Diamond, Swap, Diamond, Spade, Swap, Spade. Input that sequence to get the last key fragment.
Once you have all three pieces, take them to the smith, Malius, who is just north of the Bake Sale. He’ll notice the fragments and forge them into the Prison Key for you. Now you can return to Jevil’s cell, unlock the door, and face the chaos!
How to Beat Jevil: A Dance with the Devil
Jevil’s attacks are fast and wild, but he always shouts a voice line that tells you what he’s about to do. Learning these cues is the key to survival. For example, when he says, “Shall we play around?”, get ready for a spiral of spade bullets. When you hear, “Let’s ride the carousel game!”, stay away from the corners of the box to dodge the diagonal attacks.
His final attack, “Final Chaos,” is nuts. Giant scythes will rain down and even break the boundaries of the bullet box. The trick here is that your SOUL can also move outside the box, giving you more room to dodge.
You have two ways to win this fight, and your choice determines your reward.
- Pacifist Reward: The Jevilstail: To win peacefully, you need to tire Jevil out. Have Ralsei use his Hypnosis ACT over and over. Kris’s Pirouette can also help, but its effects are random. Once Jevil is tired, Ralsei can Pacify him to end the fight. Your reward is the Jevilstail, a great piece of armor that gives +2 to Attack, Defense, and Magic for any character.
- Violent Reward: The Devilsknife: The direct approach is to fight. Use Kris’s attacks and, more importantly, Susie’s Rude Buster spell for big damage. Defeating him this way gets you the Devilsknife, a powerful weapon for Susie that boosts her Attack and Magic and makes her Rude Buster cheaper to use.
Chapter 2 Deltarune Secret Boss: Spamton NEO, the BIG SHOT
The secret boss of Chapter 2 is Spamton G. Spamton, a tragic salesman who dreams of being a “[BIG SHOT]”. His quest is much more complex than Jevil’s, and the final battle changes the gameplay completely.
Finding Spamton NEO: A Salesman’s Grand Scheme
The path to Spamton NEO is long and has very specific requirements. One wrong move, and you can lock yourself out of the quest for good.
First, you must encounter Spamton in the alleyway in Cyber City. It is absolutely essential that you defeat him peacefully by “Accepting Deals” and “Snapping Wires.” If you attack him, he’ll run away, and you won’t be able to access his shop, which is necessary for the quest.
Next, in the Cyber Field, you have to find an NPC named the Hacker (he has a mouse cursor for a head) and complete his quest to find three blue checkmarks. You’ll need his help later.
Once you reach the Queen’s Mansion, use the warp door to go back to the Trash Zone. Head west from the warp point to find Spamton’s shop hidden in a hole in the wall. You need to buy the KeyGen item from him. His prices are crazy and change all the time, so just keep talking to him until the price drops to something you can afford.
After that, return to the Queen’s Mansion. The Hacker will be in a room full of statues. Watch him, and he’ll eventually stop in front of a wall, his cursor head changing to a hand icon. Interact with that spot on the wall to open a secret passage to the basement.
Kris has to go through the dangerous basement alone. Use the KeyGen to open a locked gate, navigate a teacup ride puzzle filled with bullets, and find an abandoned robot to get the EmptyDisk. Take this disk back to Spamton’s shop. He will transfer himself onto it, creating the LoadedDisk. Finally, take this LoadedDisk back to the robot in the basement. When you try to leave, Spamton NEO will burst out and attack!
How to Beat Spamton NEO: Now’s Your Chance!
This fight is a game changer. Your SOUL turns yellow, and you can now shoot projectiles like in a shoot ’em up game. You’ll have to dodge bullet patterns while shooting down Spamton’s attacks. You can charge up a “Big Shot” for more damage.
- Watch out for his “Pipis” attack, which sends exploding blue spheres at you. Shoot them down before they get close.
- During his “Heart on a Chain” attack, focus your fire on the main heart to end the attack faster.
- His face will even become a cannon, with his eyes, nose, and mouth firing projectiles. Try to destroy one of the parts to make the attack easier on the next go around.
Like with Jevil, you have a choice of how to win.
- Pacifist Reward: The Dealmaker: To win non violently, use the ACT command to “Snap” the wires holding him up. Each snap costs more TP, so you’ll need to graze bullets to build it up. This gets you the Dealmaker armor, which boosts your Defense and Magic and increases the money you earn from battles.
- Violent Reward: The Puppet Scarf: To win by fighting, just keep shooting and attacking with Kris and Susie until his HP runs out. Your reward is the Puppet Scarf, a weapon for Ralsei that gives him a huge attack boost but lowers his magic, turning him into a fighter instead of a healer.
A Quick Note on the Weird (Snowgrave) Route
If you are playing the alternate “Weird Route” (also known as Snowgrave), the Spamton NEO fight is no longer an optional secret but the mandatory final boss of the chapter. Kris fights him alone, the battle is much harder, and you are guaranteed to get the Puppet Scarf as your reward.
Chapter 3 Deltarune Secret Boss: The Roaring Knight, the Impossible Foe
Chapter 3 flips the script on what a Deltarune secret boss can be. Here, the challenge isn’t finding the boss, the Roaring Knight is a mandatory story opponent. The secret is discovering that it’s possible to win a fight the game tells you is impossible.
The Path to Victory: The Shadow Mantle Quest
The entire “quest” for this boss is actually the long and difficult journey to get one specific item: the Shadow Mantle. Without it, victory is practically impossible.
To even start this quest, you need to get an S Rank score on the first two “boards” of Tenna’s TV Time game show in the TV studio. This unlocks the S Rank room, where you’ll find an 8 bit console. You’ll have to play through a series of hidden minigames on this console, finding items like the Ice Key and Shelter Key.
The final minigame requires you to attack your own party members to level up, allowing you to break barriers and fight a secret mini boss, the Shadow Mantle Holder. This whole sequence is a dark reflection of the game’s “Weird Route,” forcing you to engage in twisted actions to get what you want. After defeating the Holder, you can finally claim the Shadow Mantle armor.
How to Beat the Roaring Knight: Defying Destiny
This fight is a pure battle of survival. The Roaring Knight is designed to be an unwinnable, scripted loss that moves the story forward. However, if you have the Shadow Mantle, you can defy that fate.
Equip the Shadow Mantle on Susie, as her Rude Buster is your only real source of damage. The entire strategy is to keep Susie alive. Kris and Ralsei should spend their turns defending to generate TP for Susie and using healing items. You don’t need to empty the Knight’s massive HP bar. You just need to survive long enough and deal a certain amount of damage (about 25% of his health). Eventually, after a specific line of dialogue from Susie, the Knight will unleash a final, desperate attack. If you survive that, one more hit will win you the battle.
Winning this fight is a statement. You are fighting against the narrative itself. As a reward for your defiance, you get the third Shadow Crystal, and nothing else. The victory itself is the prize.
Chapter 4 Deltarune Secret Boss: The Hammer of Justice, The Mentor
The final Deltarune secret boss in this guide returns to a more traditional structure, involving a puzzle that leads to a unique, one on one duel.
Unlocking the Duel: The Golden Piano Puzzle
This quest revolves around a Golden Piano. To solve its puzzle, you first need to find three hidden Music Sheets. To reach them, you’ll need the ClaimbClaws, an item you get from defeating the miniboss Jackenstein, which lets you climb specific walls.
- The sheets are hidden behind waterfalls and at the end of dark mazes that you can now access with the ClaimbClaws.
Once you have all three sheets, return to the Golden Piano located above the Study area. Play the completed tune, and it will open a secret passage in a nearby fireplace. Inside, you’ll find a Magic Axe. When you try to take it, the old shopkeeper Gerson appears, transforms into the Hammer of Justice, and challenges Susie to a duel to prove her worth.
You might also like this: Deltarune Chapter 4 Complete Guide
How to Beat the Hammer of Justice: A Lesson in Strength
This battle is a solo fight with Susie. It’s not about being aggressive; it’s a test of defense and endurance. The fight introduces a new parry mechanic where Susie’s SOUL turns green, and you must use an axe to block incoming arrows.
This battle is designed to be a lesson for Susie. Her usual Rude Buster is ineffective here. Instead, you need to master the parry mechanic and use her healing spell, OkHeal, to survive. The fight doesn’t end by depleting his health but by surviving a set number of turns and taking specific actions, like healing.
Once you pass the test, Gerson deems Susie worthy. She is rewarded with the Justice Axe, a very strong weapon, and you receive the fourth and final Shadow Crystal.
The Ultimate Prize: What are the Shadow Crystals For?
After all these insane battles, you’ll have a collection of Shadow Crystals. What do they do? We still don’t know for sure. They are the one constant reward, linking the chaotic jester, the tragic puppet, the impossible knight, and the wise old hammer together.
Hunting down every Deltarune secret boss is more than just a side quest, it feels like an essential part of the experience. It’s a parallel story about defying fate, uncovering secrets, and mastering the game’s deepest challenges. The journey itself is the true reward, hinting at a much larger role we have yet to play in the fate of the world.
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