Undefined
AchievementRebirthUnlock unknown
Achievement details
- Achievement number
- 125
- Description
- Unlocked a new item.
- Requirement
- Complete the Boss Rush as Eden
How do you unlock Undefined?
In The Binding of Isaac, Undefined is unlocked by earning the Boss Rush completion mark as Eden (Character).
Structured pathSource-backed requirements are mapped into trackable steps.
Unlocked a new item.
How to unlock: Complete Chapter 4
What unlocking Undefined leads to
Source: bindingofisaacrebirth.wiki.gg
Imported 2026-09-13