Grants 3 broken hearts and +0.25 damage for every broken heart Isaac has. Every otherwise fatal hit will add 2 more until Isaac has nothing but broken hearts.
Quote
"Eternal sorrow"
Effects
Grants +0.25 damage for every broken heart Isaac has.
Immediately grants 3 broken hearts. Every otherwise fatal hit will instead add 2 more, replacing other types of hearts if necessary, and deal 40 damage to all enemies in the room.
Once Isaac has no non-broken hearts left, he dies. Extra lives will apply at this point.