So, Chapter 4 of Deltarune finally dropped. Honestly, after years of waiting and staring at those "coming soon" newsletters, June 5, 2025, felt like a fever dream. But here we are. Most of the community is currently losing their minds over the Roaring Knight’s identity or whatever the hell Kris is doing with that knife in the bathroom, but there’s one specific encounter that caught everyone off guard. It’s weird, it’s creepy, and it’s arguably the most mechanical "test" Toby Fox has ever thrown at us.
I’m talking about the Sound of Justice.
It’s not just a boss. It’s a mindless, hostile reflection of one of the most beloved characters in the Undertale/Deltarune mythos: Gerson Boom. If you’ve played through the Second Sanctuary, you know exactly the moment it all goes south. Susie creates a Dark Fountain—which, by the way, is a massive lore bomb on its own—and accidentally brings a statue of the legendary smith to life.
But it’s not Gerson. It’s something else entirely.
What is the Sound of Justice Deltarune Boss?
Basically, the Sound of Justice is a homunculus. It’s a "monstrulum," as some fans have dubbed it, born from Susie’s subconscious and her deep, somewhat tragic respect for Gerson. Remember, in Chapter 4, Susie is dealing with the reality of Gerson’s death. She wants a mentor. She wants the "Hammer of Justice." What she gets instead is a hollow, brown stone-and-wood construct that wears a helmet with vertical slits and moves with a twitchy, mindless aggression.
It doesn’t talk. It doesn't have a grand monologue about the prophecy. It just laughs—that distorted, gravelly Gerson laugh—and starts swinging.
The Fight That Breaks Your Ears
This is where Toby Fox really flexed his "troll" muscles, but in a way that’s actually super innovative. The Sound of Justice Deltarune fight is essentially a rhythm and audio-cue survival challenge.
Initially, you’re in total darkness. Susie thinks she’s found Gerson, but then the arrows start flying. If you’re playing with headphones, you’ll notice something immediately: the game is screaming at you. Literally. A voice tells you "Left," "Right," or "Up," and you have to snap the Green Soul to block.
- The Sound Trap: As the battle progresses, the visual cues (the flashes of light) actually disappear. You are left staring at a black screen, relying entirely on directional audio.
- The Accessibility Twist: If you’re like me and you tried to be "funny" by failing the initial sound check at the beginning of the chapter, the game actually leaves the visual cues on. It’s a built-in "Easy Mode" for players who might have hearing difficulties or just really bad headphones.
- The Hammer Drop: Once the SOUL turns red, you have to dodge a massive hammer silhouette. If you haven't been practicing your reaction times, this part is a nightmare.
One thing people get wrong is trying to "FIGHT" it. You can't. If you select FIGHT as Kris, it misses every single time. Susie eventually has to be the one to end it by using her healing magic, which reveals the "enemy" is just a crumbling statue. It’s a heartbreaking moment. Susie is trying to heal a memory that’s already dead.
Why This Fight Matters for the Lore
There’s a popular theory floating around Reddit that the Sound of Justice is aggressive because it was created by Susie’s fountain specifically. Unlike the "wacky" Darkners in the Cyber World or the TV World, the Second Sanctuary feels... off.
It’s representative of Susie's trust issues. Think about it. She finally finds someone to look up to—the Old Man—and her own Dark World turns him into a mindless killer that attacks her without provocation. Ralsei doesn't even hesitate to destroy it once the light comes back. He treats it like garbage. Like it shouldn't even exist. That says a lot about what Ralsei knows regarding "artificial" Darkners.
Real-World Strategies for Beating the Statue
If you're stuck on this fight, here is what you actually need to do.
- Check your Stereo: If your headphones are Mono, you are going to have a bad time. The audio cues are directional.
- Equip the Best Armor: You aren't winning this by dealing damage. You win by surviving four turns until Kris shows up, and then lasting until Susie decides to use her magic.
- Tension Gems: If you want to end the fight early, use a Tension Gem to get enough TP for Susie’s BetterHeal. If you trigger the heal yourself, the battle ends instantly.
- Don't Panic at the Laugh: The distorted laugh signifies a hammer slam. When you hear it, look for the white rectangle on the board and move immediately.
The Music of Justice
We can't talk about this boss without mentioning the track "Hammer of Justice" (Track 58 on the Chapters 3+4 OST). Toby Fox, along with contributors like Lena Raine, absolutely cooked here. It’s a chaotic remix of "Spear of Justice" and "Battle Against a True Hero," but slowed down and layered with these weird, industrial grinding sounds. It perfectly captures the feeling of a hero’s legacy being twisted into something unrecognizable.
It’s a stark contrast to the earlier Chapter 4 tracks like "Gyaa Ha ha!" which felt more like the Gerson we knew. This one is pure tension.
Actionable Next Steps for Completionists
If you’ve already cleared the Sound of Justice, don't just move on to the next area. There are a few things you probably missed in the Second Sanctuary:
- Find the Broken Shard: Go back to the room where the statue first appeared after Ralsei breaks it. There’s a "Statue Fragment" you can pick up. Taking this back to the Smith in Castle Town allows you to craft the Cracked Shield, which is essential for the later secret boss in Chapter 5.
- The Dialogue Variant: Try playing the fight again on a different save, but this time, don't use any items. If Susie gets downed before Kris arrives, the dialogue changes significantly, showing a much more vulnerable side of her character that doesn't often come out.
- The Piano Mystery: There is a golden piano hidden above the Study. If you’ve found the three segments of sheet music throughout the chapter, you can play them here. It doesn't trigger a boss, but it gives you more context on why the Sound of Justice looked the way it did.
The Sound of Justice isn't the hardest boss in Deltarune, but it's the one that lingers. It reminds us that even in a world of magic and darkness, you can't really bring back what's gone. You just end up with a statue that hits you with a hammer.