The Hammer of Justice is the fast, heroic Gerson boss theme from Deltarune Chapter 4, used for gaming edits, comebacks and triumphant reveal moments.
The Hammer of Justice is Gerson's boss theme from Deltarune Chapter 4, a full-throttle instrumental built around pounding drums, urgent strings and a bold, looping melody that feels like a hero stepping into a final showdown. The track keeps building instead of settling, with sharp hits and quick runs that create constant forward momentum. It sounds righteous, theatrical and slightly over the top, which is why a simple entrance, comeback or victory can suddenly feel like a boss fight. Played over ordinary footage, it turns the moment dramatic, heroic and funny at the same time.
The Hammer of Justice comes from Deltarune, the role-playing game by Toby Fox, and is the boss theme for Gerson in Chapter 4, released in 2025. Gerson, the elderly turtle first met in Undertale, returns here as a heroic mentor figure who tests Susie in battle, and his theme mixes playful energy with real weight. After the chapter launched, players clipped and shared the track online, and editors soon borrowed it for other games and videos. It remains popular because the righteous, old-hero energy is instantly recognisable, even for viewers who have never played the fight.