Calamity Mod Wiki
Iron Heart
  • Iron Heart.png
Stack digit 1.png
Use time45 Very Slow
TooltipHealing with potions and all positive life regen is disabled.
Enemy damage scales with your max health.
Can be toggled on and off.
RarityRarity Level: rainbow
SellNo value
Hearts after using the Iron Heart

The Iron Heart is an item placed in a newly spawned player's inventory. Upon being used in Expert Mode, it enables or disables several effects on every character in the current world:

  • Natural Health regeneration is completely disabled.
  • Recovery Potions cannot be used.
  • Direct damage taken by the player now deals a minimum amount of damage, dependent on the player's max HP. The minimum damage is calculated as 40 + 10% of the player's max HP. Hits that would deal more damage than this minimum will deal their normal damage.
    • If the taken damage is below (and therefore becomes) the minimum damage, it plays a softer custom hurt sound.
    • If damage taken is above the minimum damage it plays a louder custom hurt sound.
    • This minimum damage is not affected by any Damage Reduction.
  • A secondary effect of Iron Heart is that the player's life hearts will become light gray in appearance, with black 'eyes' on either side of each, matching the appearance of being heart-shaped skulls. They remain with this appearance even after using Life Fruits or other permanent power-ups.
  • The player will have a custom death sound.


  • The Iron Heart's effects are tied to the world it was used in, rather than the player that used it. This means that all players that join a world in which the Iron Heart has been used will have the Iron Heart's effects, even if they don't use the item.
  • Hearts and Lifesteal will still heal the player.



  • The appearance of the life hearts after using the Iron Heart is a reference to the game Hollow Knight, in which the player's mask-based life meter bears a striking resemblance.
    • This item's name is a reference to Hollow Knight's perma-death mode, known as "Steel Soul".
  • The life hearts' appearance also references the life hearts in Minecraft's perma-death mode known as "Hardcore", as the mode causes the player's hearts to develop eye-like streaks.
  • In previous versions of the mod, this item made dying while a boss is alive permanently kill the player in a similar manner to Hardcore.
    • Additionally in previous versions of the mod, this item became unusable after a minute of runtime in the world.