Blue Key
AchievementRepentanceUnlock unknown
Achievement details
- Achievement number
- 493
- Description
- ???
- Requirement
- Defeat The Beast as Tainted Cain
How do you unlock Blue Key?
In The Binding of Isaac, Blue Key is unlocked by earning the The Beast completion mark as Tainted Cain.
Structured pathSource-backed requirements are mapped into trackable steps.
???
- A Strange Door is unlocked by beating Mother for the first time. source
- Take The Polaroid or The Negative after Mom, escape the boss room, then use it to open A Strange Door. source
- Find Dad's Note, complete the Ascent to Home, then defeat Dogma, the Ultra Harbingers, and The Beast. source
How to unlock: Use Red Key (etc.) to open the hidden closet in Home as Cain
What unlocking Blue Key leads to
Source: bindingofisaacrebirth.wiki.gg
Imported 2026-09-13