Brittle Bones

ItemAfterbirth+Locked

passiveGame ID 549★★★★

How do you unlock Brittle Bones?

In The Binding of Isaac, Brittle Bones is unlocked by earning the The Lamb completion mark as The Forgotten (Character).

Structured pathSource-backed requirements are mapped into trackable steps.

Replaces all Red Heart with 6 empty Bone Hearts. [Before Repentance] Upon losing a Bone Heart, Isaac fires bones in 8 directions and permanently gains a tears up. [Repentance] Upon losing a Bone Heart, Isaac fires bones in 8 directions and permanently gains a fire rate up.

Brittle Bones (Achievement)
- The Forgotten (Character) → The Lamb (normal)
  1. Defeat Satan 5 times to unlock The Negative. source
  2. The Negative is a guaranteed drop from Mom; take it, then defeat Satan in Sheol and touch the chest to enter Dark Room. source
  3. Find and defeat The Lamb in Dark Room. source
  - The Forgotten (Character)

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What unlocking Brittle Bones leads to

Nothing depends on this yet.

Source: bindingofisaacrebirth.wiki.gg

Imported 2026-09-13