正義之矛(Spear of Justice) 是Undertale 的原聲帶專輯里面 第46首歌。
在完美路線和中立路線里面 跟 Undyne 战斗时就会播放。
Its melody is based on "Undyne" and the "Ruins" melody, more specifically, the version of it in "Waterfall."
It is a longer, slightly modified version of "NGAHHH!!" with more sections added.
- 正義之矛 is a reference to Gerson's former title, "The Hammer of Justice."
- When closely listened to, "Spear of Justice" resembles "Passionate Duelist" from Yu-Gi-Oh! Duel Monsters.
- A sped-up version (about 1.25x) of this song plays in the mock battle with Undyne.
- There is an alternate version of Undyne's Battle theme, but it was scrapped since it didn't sound like "being heroically punched in the face."