ALL Secret Bosses in Deltarune - Chapters 1-5

Deltarune, Toby Fox's episodic follow-up to Undertale, has a tradition tucked away in every chapter: a hidden, optional boss far nastier than anything the main story asks of you. They're not required and they're easy to miss entirely, yet they're some of the toughest, strangest and most lovingly made fights in the whole game. They're also quietly connected.

Here's every secret boss so far and what makes each one worth hunting down.

WARNING: spoilers ahead for all chapters!

Jevil

Jevil is the former Court Jester of Card Kingdom, locked away after a meeting with a "strange someone" sent him spiralling into the belief that the whole world is just a game.

How to unlock:

• Late in the chapter, inside Card Castle, take the south-eastern elevator and pick the mysterious "??????" floor. Head down the stairs and speak to Jevil in his cell - he'll ask you to find the key that frees him.
• Piece one: ask Seam, the old shopkeeper out in the Field, about the strange prisoner.
• Piece two: in the Forest area with the dancing Paper Dancers, slip south-west onto a hidden dark path that looks like thin air, see off the Rabbicks waiting there, and grab it from the chest.
• Piece three: head north through the gates from the Field, past a Jigsawry battle, to a suit-symbol puzzle. Solve it by reading the suit symbols on Card Castle's floors from the following order: Diamond, Heart, Club, Spade.
• Take all three pieces to Smith Malius at the Bake Sale to fuse them into the Prison Key, then return to the cell and open it.

Beat him, peacefully or violently, and the reward shifts to match - the Jevilstail armour for mercy, the Devilsknife for force - along with a Shadow Crystal.

Spamton NEO

A glitchy salesman puppet from the Cyber World's Trash Zone, Spamton is desperate to cut his own strings and become a "BIG SHOT".

How to unlock:

• During the alleyway "deals" fight, don't beat him through violence - take his final deal.
• Head to his shop in the Trash Zone and buy the KeyGen, waiting for the cycling price to dip under 100 Kromer.
• Go into Queen's Mansion and find the hidden basement: there's a concealed switch on a potted plant on the first floor, just past the room with the cars.
• Down in the basement, prise the EmptyDisk from a robot corpse.
• Take it back to Spamton; he'll swap it for a LoadedDisk.
• Return to the same machine and reinsert the disk. As you turn to leave, Spamton NEO ambushes you.

He leaves you the Dealmaker or the Puppet Scarf, plus another Shadow Crystal.

The Roaring Knight

Chapter 3 is a bit different. The Knight is the overarching antagonist of all of Deltarune, the figure tearing Dark Fountains out of the earth, and this time there's no puzzle to solve - the Roaring Knight simply turns up at the very end of the chapter, one-shots the actual final boss, and rounds on you. Finding it isn't the challenge - surviving is!

The intended way through is the Shadow Mantle, a piece of defensive armour you earn by defeating the Shadow Mantle Holder.

How To Unlock:

• Score S Rank on both TV Time boards.
• In the S Rank changing room, talk to the NPC in the top-left and sit through everything the secret game shows you - across three separate visits.
• On the third visit, you'll face a shadow mini-boss. Beat it and the Shadow Mantle drops.

You don't strictly need the Shadow Mantle to defeat the Roaring Knight, but it is incredibly hard to defeat the Roaring Knight without it. Defeat the Knight, and you claim Chapter 3's Shadow Crystal.

The Hammer of Justice

Chapter 4's secret boss is Gerson Boom, the "Old Man" and a returning face from Undertale, here a Darkner revived by the Dark Sanctuaries. In life he was a blacksmith turned celebrated author of the Lord of the Hammer series. In death, clad in silver armour and swinging an enormous war hammer, he becomes the Hammer of Justice.

How to unlock him:

• Beat the Jackenstein mini-boss and pick up the ClaimbClaws, which let you scale the Sanctuary's book-ladders.
• Track down three music pieces back in the chapter's earlier areas: one to the west past the room of patrolling puffballs (behind a watery mini-boss), one to the east through the stained-glass hallway and a pitch-black room, and one behind the waterfall through a maze of bells.
• Play all three on the golden piano above the Study. (If you'd rather skip the hunt, the notes are Up, Centre, Up, Left, Down, Centre, Right, Centre, Right, Down, Left, Centre.)
• A secret path opens behind the Study fireplace - save your game before you head in, as you can't use items in the fight.

The boss at the end drops one of the chapter's best items for Susie, plus the Shadow Crystal that completes your collection for now.

Chapter 4 also tucks away a second, far gentler secret boss:

• Recruit everyone back in Chapter 3 - it's unreachable otherwise.
• Head to the TV building in Castle Town and go all the way to the left.
• Read the note by the mysterious door, then enter the code 6453.

It won't hand you a crystal or any gear, but clearing it unlocks a set of bonus minigames.

Mad Mew Mew (Pink)

Chapter 5's secret boss is Pink, better known as Mad Mew Mew - the possessed Mew Mew Kissy Cutie doll turned Darkner, here serving as the chapter's Shadow Crystal boss (and possessed by a ghost Lightner during the fight itself). She's locked away behind a pink door.

How to unlock it:

• Across the chapter, collect 10 pink coins, usually tucked behind puzzles and platforming gimmicks. Some appear early, so you may need to progress a fair way before you can reach everything, then backtrack for any you missed.
• • For a detailed look at the locations of the coins, check our Pink Coin Location Guide!
• Spend the 10 coins on the Mysterious Key at the Cliff Shop.
• Near the end of the chapter, at the top of the castle, head left rather than pressing on toward the fountain - Ralsei will note you're going the wrong way. Drop into the pit below and follow it to the locked pink door.
• Use the Mysterious Key on the door to reach Mad Mew Mew.

Like every Deltarune secret boss, expect a sharp difficulty spike and dense bullet patterns, so save and stock up on healing first. Beating her yields the chapter's Shadow Crystal.