Tough Heart introduces a new mechanic: defense. It has 20 HP just like a Lesser Heart , but it has 4 defense. This means that all damage sources do 4 less damage to this heart, giving it a much higher survivability. Tough Hearts can be acquired in the shop and in item rooms.
Tough Heart is extremely powerful in the early game, and retains its usefulness throughout late game. When equipped with one or more Harder Hearts items, it becomes a formidable tank that can survive a large number of smaller bullets. However, against Amorphous bosses, tough heart falls short of survivability because it is unable to tank very many big bullets. Swapping out is recommended during those bosses. In dream, always put Jumbo Heart to the right of Tough Heart unless you have more defense upgrades. In previous floors, smaller bullets work better with tough heart while big bullet bosses work better with jumbo.
- With two harder hearts, Tough Heart only takes 0.5 damage from smaller dream bullets and takes no damage from previous small bullets
- Tough Heart used to outclass Jumbo in many places before buffs to bullet damage, especially in later floors