Magic resistance (monster)
Monsters have innate magic resistance, also known as MR. This is separate from the magic resistance provided via various worn or carried items. It is given as a number from 0 to 100. This is frequently given as a percentage, although this is not entirely accurate.
Monsters' magic resistance allows them to resist various attacks, generally of a "magical" nature. It is handled by the resist() function. If a monster successfully resists an attack, it takes roughly half damage.
The chance of a monster resisting is given as follows:
Chance = MR/(100 + (attack level) - (defense level))
which is only equal to MR as a percentage when attack and defense level are equal. Zero MR monsters will never resist.
Attack level is calculated as follows:
Defense level is the level of the defending monster (max 50).
All this also determines the chance monsters (including pets) resist conflict. Conflict always counts as ring.
Monsters can also gain player-style magic resistance by wearing a cloak of magic resistance, gray dragon scale (mail), and wielding/carrying Magicbane, or certain quest artifacts. In addition, a few monsters have it intrinsically, separate from their monster MR. However, its scope is loosely smaller than monster magic resistance. For example, taming and conflict are not affected, while polymorph traps become ineffective. Neither type of magic resistance will protect monsters from level teleporters.
- <Foo> resists!
- A monster resisted an attack. Shown only in some cases.
FIQHack and NetHack Fourk call this willpower to distinguish it from magic resistance. Except for this, it generally works the same as in vanilla, except that in FIQHack, the attacker bonus from wands depends on wand skill.
A user has suggested improving this page or section as follows:
"A list of all effects subject to monster mr, and/or confirmation that all those effects mention they are subject to it and link here."