In addition to harming the player and monsters, fire in NetHack can damage items. Fire damage comes from the following sources:
- Fire rays
- Fireballs and fiery explosions
- Towers of flame
- Melee attacks of a fire ant, a fire elemental, or a salamander
- Explosion attack of a flaming sphere
- Passive attack of a red mold, a fire elemental, or a fire vortex
- Gaze attack of a pyrolisk
- Holding attack of a salamander
- Engulfing attack of a steam vortex or a fire vortex
- Bonus damage of the artifact Fire Brand
- Contact with lava
- A thrown or drunk lit potion of oil
Fire is also mentioned in the following places:
- The Plane of Fire is the third of the Elemental Planes.
- Accepted sacrifices on a neutral or chaotic altar explode in a "burst of flame". This fire is cosmetic and does not interact with you, so there is no damage to you or to your inventory.
Fire burns organic material and boils liquids. Fire attacks are likely to damage worn armor made of cloth, leather, or wood (such as shirts, cloaks, and shields), and destroy scrolls, spellbooks, and potions. The scroll of fire is an exception: it will never be destroyed by fire attacks.
Fire rays and explosions may boil away pools of water in the dungeon, leaving behind pits. This only applies to water in "pools"; "moats" and "water" tiles are unaffected. For more information on the distinction between these types of terrain, see Moat#Pool vs. moat vs. water.
Damage to yourself or your inventory can be prevented or minimized by the following:
- Resistance: Intrinsic or extrinsic fire resistance prevents or reduces hit point loss from fire attacks. It does not prevent erosion of worn equipment or destruction of items in your main inventory.
- Reflection: Fire rays and breath attacks can be reflected, preventing damage to yourself and your items. Nondirectional attacks (melee, passive attacks, explosions) cannot.
- Containers: Items in containers are safe from fire damage.
- Fireproofing: Armor made of cloth, leather, or wood can be fireproofed, protecting it from damage from fire. Fireproof armor does not prevent fire damage to the player, except in one case. It is possible to get fireproof scrolls, potions, and spellbooks by wishing, but this is probably impractical.
- Magic cancellation: High MC can protect your inventory from melee fire attacks. It does not prevent damage from passive or engulfing fire attacks, or from explosions or ray attacks.
- features the new role of Flame Mage and the artifact athame named Firewall, which deals fire damage.
- The following SLASH'EM monsters have fire attacks: lava blobs, hellcats, hellrats, movanic devas, hellbats, fire vampires, wax golems, ruby golems, and crystal golems.