Chapter 1 of Deltarune features a secret boss that you might have missed on your first playthrough. While Toby Fox, the developer behind both Undertale and Deltarune, is working on releasing more chapters, you may not have discovered every secret within the chapters that already exist. One of these secrets is Jevil, who is the most difficult boss battle in the game.

While you wait for Chapters 3-5 of Deltarune, you can seek out and battle this challenging secret boss. But before you can fight Jevil, you'll have to find him. Jevil can be found hiding within the Castle, the final location of Chapter 1, and players will need all three keys in order to unlock the door to him. Although it's a challenge, there are ways to defeat Jevil if you're prepared for the fight.

How to Unlock The Secret Boss In Deltarune Chapter 1

Gathering The Broken Keys To Free Jevil

After clearing out the Castle Dungeon, walk past the shop and take the elevator to the first floor. Head down and to the right to find another elevator with the floor '????" and walk downstairs. After getting out of the elevator, follow the path to find Jevil.

Speak with Jevil, and he will tell you that you must find a key to unlock the door. The key itself can be found by speaking with Seam, the Shopkeeper, found at the field in the shop. Speak with him and choose the "Strange Prisoner" dialogue option. This will give you the Broken Key item, which you'll need to fix to open the door.

After grabbing the Broken Key in Deltarune, the game will provide hints on where to find the rest of its pieces. To find the first piece, fast-travel over to the Bake Sale and move left. Walk past the area where the two Bloxers are and keep moving to find a room with the black and white dancers that block the path ahead. Take the path to the south and continue until it seems that Kris is walking off the path and on air.

Keep moving forward and follow that secret path to find a new section with Rabbicks to battle or run from. Follow this path to find the second piece of the key.

The third and final piece can be found in the Field. Fast travel to this location and head to the right until you reach the puzzle from earlier in the game. This time around, you'll need to set the combination to Diamond, Heart, Clover, and Spade. This will unlock the final piece of the key.

Now, all you need to do is fix the key to make it usable. To fix the key, you will need to go back to the Bake Sale. Take the path to the north to find Smith Malius, who will notice the broken key pieces in your inventory and offer to fix them.

With the fixed key, you're finally ready to take on Jevil. Before you run into battle, make sure to prepare by stopping by the shop to buy healing items and prepare for the fight. Head back to the elevator with the question marks and approach the gate to start the battle now that you have found Deltarune's secret boss.

How to Defeat The Secret Boss In Deltarune Chapter 1

Fast Projectiles and High Defense Stats

As with most Undertale and Deltarune fights, you have two approaches to this encounter: the option to go ive or violent . Going peacefully will reward you with Jevilstail Armor, while choosing violence is how you get a hold of the Devilsknife. The choice is up to you, depending on what kind of run you're doing. Either way, this is the most difficult battle in Deltarune: Chapter 1, which means that you'll need to practice reading Jevil's moveset and get comfortable dodging his attacks.

I suggest going into this battle with a fair number of consumables to keep the entire party healed, as several of Jevil's attacks are hard to avoid and can take down an unprepared party member. Additionally, having the party fairly rounded out with solid Defense stats across the board will help you withstand a hit or two and keep going.

Fortunately, most of his attacks have text cues, making it easier to determine which move he will do. The table below explains what happens when Jevil uses a particular piece of dialogue and what you might be able to do to dodge it. It will take some patience to get used to these moves, so don't be discouraged if it takes a few tries. These attacks play out in phases, starting in a specific order before becoming random the longer Jevil spends on a phase.

Once you get through all of these moves, Jevil will begin to go into his desperation mode. During this time, all the attacks from above will be used simultaneously and at different speeds. The combat box will also be removed as knives rain from the top of the screen. This is the sign that the battle will soon come to a close. This also allows you to move around outside the play area, making it easier to dodge the knives.

Defeating Jevil or causing him to give up will reward you with either his knife or a piece of armor. No matter how you finish the encounter, Jevil will prophesize doom on the party and disappear.

Note that you do not need to clear out the rest of the chapter to attempt this fight. It becomes available at any point after making it to the Castle, so you can tackle Jevil anytime that you want over the course of your run. With the release of Chapter 2, you can also jump back into Chapter 1 to take on Jevil if you missed it during your initial playthrough (which is very likely since it's hidden). With Deltarune Chapter 3 and 4 coming soon, it might be a good idea to revisit this secret boss encounter in the first chapter.

The rewards for completing this challenge might be small, but they can be carried over into Chapter 2. It's likely all items can be carried over into future chapters so keep those save files safe until the wait is over. Although this might not even be all that necessary, since Deltarune's predecessor Undertale famously re all save files, even if you delete them.

Before Chapter 1 version 1.07, the Shadow Crystal didn't show up in your inventory, and was only discovered when speaking with Seam in Chapter 2.

Defeating Jevil also rewards you with a Shadow Crystal. This mysterious item is only acquired from Jevil in Chapter 1 and Spamton NEO in Chapter 2. You can bring the crystal to Seam, who will comment that Shadow Crystals can be found with powerful beings and that even though it's invisible, it still casts a shadow.

Luckily, Deltarune is available now on most modern consoles, which means you can try different runs on different consoles without making multiple s. However, be prepared for your ending to suffer if you choose the more violent route, regardless of when the next chapters come out. Until then, keep attempting to beat Jevil until you defeat him in Deltarune.