Acid resistance
Acid resistance is a property that appears in NetHack and protects against acid damage.
Sources
Acid resistance can be obtained by wearing yellow dragon scales, yellow dragon scale mail or an alchemy smock. It can also be obtained by polymorphing into any acidic monster, as they are the only monsters to have the intrinsic property.
Acid resistance does not protect your equipment against acidic erosion – this is done by corrodeproofing it.
The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that the information below is still accurate, then update the page to incorporate it.
You may gain temporary acid resistance by eating the following corpses: acid blob, spotted jelly, ochre jelly, yellow dragon, green mold, black naga, green slime, Chromatic Dragon.
Extrinsic sources of acid resistance also protect your inventory from acid damage 99⁄100 of the time.Strategy
Sources of acid damage are as uncommon as acid resistance itself - even in scenarios where it can do significant damage, you can often easily avoid it by other methods, e.g. ranged attacks for acidic passives, and reflection for acid breath. Yellow dragon scales may still be worthwhile for pets and polyforms with multiple hit dice, particularly mind flayers.
The following information pertains to an upcoming version (3.7.0). If this version is now released, please verify that the information below is still accurate, then update the page to incorporate it.
Per commit 0891ef4, monsters now gain acid resistance from a worn alchemy smock, allowing for more variety in equipping humanoid pets. Additionally, yellow dragon scale mail also grants resistance to stoning.Variants
SLASH'EM
In SLASH'EM, the alchemy smock has been replaced by the lab coat, which also provides this extrinsic as well as MC3. Some new monsters deal massive amounts of acid damage, most notoriously the giant shoggoth, making this property more desirable for an ascension kit. Though still not a must-have, a player who has magic resistance, reflection, drain resistance, and magic cancellation through other means may opt for a lab coat or yellow dragon scale mail just to be on the safe side.
UnNetHack
In UnNetHack, chromatic dragon scales and chromatic dragon scale mail provide acid resistance among numerous other extrinsics.
FIQHack
In FIQHack, extrinsic acid resistance protects your items from corrosion.
EvilHack
In EvilHack, due to the presence of monsters such as acid spheres and buffs to existing acidic monsters along with the addition of the highly-damaging acid blast monster spell, sources of acid resistance such as yellow dragon scales and scale mail are far more valuable. Dragonbane is changed to a pair of dragonhide gauntlets that provide acid resistance in addition to the standard reflection and warning of dragons, making it a highly sought-after artifact for most players.