Resistance

From Wikihack

Resistances protect you against several harmful effects that you may encounter in the dungeon. A resistance can be either intrinsic, meaning a natural resistance, or extrinsic, meaning a resistance gained by wearing or wielding a certain item. Many intrinsic resistances can only be gained by polymorphing into a certain creature, which is not very convenient.

There are eight or nine different resistances, depending on whether you count reflection as one of them. Each resistance maps into a dragon of certain color — a dragon of that color has that resistance as intrinsic. The resistances are: