Erosion

Erosion is an attribute that can apply to some items depending on their material. The performance of an eroded weapon or piece of armor will be degraded - weapons will have their damage decreased and armor's intrinsic AC bonus will be reduced by one for each level of erosion (not affecting enchantment). This means a +0 dwarvish iron helm's AC is -2, while a thoroughly rusty +1 dwarvish iron helm's AC is -1. The following types of erosion exist:

Rust affects only items made from iron. It results from exposure to water (by potion, fountain, pool, etc.) or to a rust monster.

Corrosion affects copper or iron items. Exposure to acidic environments (potions or some [[monsters) results in this form of damage.

Burning affects any organic material or plastic, and results from e.g. fire traps.

Rotting also affects any organic material and most commonly results from exposure to brown puddings.

Items can suffer up to three levels of erosion, for example: rusty, very rusty, and thoroughly rusty. An item can be both thoroughly rusty and thoroughly corroded, but it will never suffer more than 3 points of damage.