Slipped Rib is an unlockable passive item added in Booster Pack #5.
- Spawns a bone familiar that circles around Isaac and reflects enemy shots.
- The reflected projectiles deal 5 damage if they would've hurt Isaac for half a heart, and 10 for a full heart. Enemy damage modification from item effects or by stage does not affect this.
- The familiar does not deal contact damage, but will kill the same types of flies on contact as Pretty Fly orbitals do.
- Despite being an orbital familiar, it is not in the list of items which Tainted Lost cannot find in regular item pools.
- BFFS!: Does not increase the reflected damage.
- This item is a reference to slipping rib syndrome.
- This item may be a reference to the Adam and Eve story in Genesis, where God takes a rib from Adam's body to create Eve.
- This item may be a reference to the NES game Castlevania 2: Simon's Quest, where Dracula's rib is an item used as a shield that protects from projectiles.
- This item is Edmund's favorite Booster Pack item according to _Kilburn.
Concept art for Slipped Rib on the right side, along with other Booster Pack items and trinkets, by Edmund McMillen.