This item is difficult to use for anyone with red health, as it is impossible to have no red hearts without removing all heart containers (such as through Devil deals). It is best used by characters that cannot gain red health at all, such as ???.
Characters can now deplete their red health fully through sources like Blood Donation Machines while having other hearts like soul hearts. As a result, this item is usable for a wider amount of characters, and has synergies with characters who prefer to have no red health (such as Eve).