There are plenty of secrets to unravel in Deltarune, but the best kind are fights you can easily miss. One of these battles is the Deltarune Chapter 4 secret boss, but beginning this encounter isn't exactly straightforward.
Before you fight this boss, we can also fill you in on Deltarune Chapter 3 and help you out with the Deltarune Chapter 3 secret boss. Or maybe you just need to get up to date with all the Deltarune characters you can meet.
Here's everything in our Deltarune Chapter 4 secret boss guide:
Who is the Deltarune Chapter 4 secret boss?
The Deltarune Chapter 4 secret boss is Old Man Gerson, also known as the Hammer of Justice. This is obviously a bit of a spoiler, but if you clicked on this guide, you knew what you were getting into.
What rewards does the Deltarune Chapter 4 secret boss drop?
After you defeat the Hammer of Justice, you receive a Justice Axe that, when equipped to Susie, increases her attack by 12, and a Shadow Crystal. We still don't know the purpose of these crystals, but you receive one after each secret boss.
How do I find the Deltarune Chapter 4 secret boss?
First, you need to complete the Deltarune Chapter 4 piano puzzle. We have a complete guide full of hints and tips if you want to do it mostly on your own merit. However, if you want to skip all of that, here are some concise bullet points that cut out the hard parts:
- Progress through Chapter 4 up until you defeat Jackenstein and receive the Claimb Claws
- Return to the Old Man's study before heading out the back door and climbing up the closest stack of books
- Once you reach the golden piano at the top of the stack of books, enter these notes: up, dot, up, left, down, dot, right, dot, right, down, left, dot
- The fireplace in the Old Man's study will open, head through this door to reach the secret boss
How do I beat the Deltarune Chapter 4 secret boss?
The fight with Hammer of Justice is a one on one battle with Susie and is all about survival. You must attack the Old Man, but you mainly need to hone your dodging skills to overcome this battle.
Here are Hammer of Justice's attacks that you need to combat:
- Susie's axe will appear in the middle of a green box and you must move it around to deflect arrows coming from the left, right, top, and bottom of the screen
- In a later phase, the box turns into an octagon and you have to block arrows diagonally as well
- A turtle shell will bounce around the screen leaving stars in it's wake that you must dodge
- Hammer of Justice will quickly shower a large number of hammers above you with a small gap you can use to dodge, he'll then launch one final large hammer
- Towards the end of the fight, Hammer of Justice will slash vertically, horizontally, or diagonally, you can see where he will slash thanks to a white box
In between his attacks, make sure you use OK Heal when needed. Good luck out there!
That's it for our Deltarune Chapter 4 secret boss guide. For more content like this, check out our Deltarune Chapter 5 guide and list of the best games like Undertale.