Defeating **Jackenstein** unlocks the climbing gear, allowing access to vertical zones that were previously blocked. This item is *mandatory* for progressing through the game’s later sections.

FAQ

Q: Where is Jackenstein in Deltarune Chapter 4?

Located behind the Delta Rune door in the northwest library, accessible after solving piano puzzles and collecting eight musical notes.

Q: Is Jackenstein a required boss?

Yes. Defeating him is necessary to obtain the climbing gear and advance the story.

Q: How do you damage Jackenstein?

Activate the *Unleash* ability from the Act menu at **60% TP** to counterattack during the maze sequence.

Q: How do you build TP in this fight?

Collect glowing orbs within the maze and repeatedly use *Defend* to charge TP each turn.

Q: What do you get for beating Jackenstein?

The **climbing tools**, required to continue Chapter 4’s main objectives.