For the trinket with a similar name, see Found Soul. For another trinket with a similar name, see Your Soul.
Lost Soul is a passive item added in The Binding of Isaac: Repentance.
- Creates a ghostly familiar that closely follows behind Isaac. It dies in one hit, respawning at the start of the next floor.
- If Lost Soul survives until the start of the next floor, it rewards Isaac with one of the following:
- Floors completed during the Ascent count.
- Waiting until after the floor is cleared before picking up Lost Soul nearly guarantees a reward payout on the next floor.
- The ghost can take explosive damage from Isaac, e.g. via placing a bomb.
- BFFS!: Gives Lost Soul a once-per-room shield, similar to Holy Mantle.
- If BFFS! is dropped, the shield will still remain active until taking one hit of damage, acting similarly to Holy Card.
- Forget Me Now: Restarting a floor prompts Lost Soul to give a reward if it's alive when used.
||If Lost Soul is killed before the segment with Mother's Shadow, it will respawn after Isaac returns to the normal floor.
||Lost Soul can die if it touches projectiles generated by friendly enemies (spawned from Mystery Egg, for example).
||Swapping Lost Soul for another item as Tainted Isaac and picking it back up again will cause it to respawn if it died previously. This can also be accomplished with Butter!.