Magic resistance

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Version 0.17: This article may not be up to date for the latest stable release of Crawl.

Magic resistance (MR) is the ability to resist hostile enchantments such as slow, confusion, banishment to the Abyss and disintegration.

The higher a being's MR, the less likely that it will be affected by an enchantment cast on it. Beings that are magical in some way (such as elves or sirens), magic-users, and those that are non-natural tend to have higher MR than other creatures.

Monster MR is partly based on hit dice, so monsters with high hit dice tend to be highly resistant to magic. Most monsters with one hit die have a 50% chance to fail to resist outright, in addition to the normal saving throw. Finally, some monsters are outright immune to magical enchantments - for instance, most nonliving creatures.

Contents

Resistible Enchantments

Some of these effects can come from potions, weapon brands, clouds, or spells that are not considered enchantments.

MR does not prevent effects triggered through the spell Alistair's Intoxication.

Notes

  • Many of these enchantments can be resisted via other means. For instance, life protection counters the effects of Agony (but not the Pain spell). Undead, nonliving, and plant monsters cannot sleep.
  • Polymorph will not be resisted by (very) ugly things, which will always change color. Shapeshifters can only resist it if they are currently in the form of something immune to magic.
  • Effects produced by the chaos brand don't check MR.

Saving throws

Resisting an enchantment is dependent on the resisting creature's MR and the enchantment power (which is a function of the spell power) of the enchantment it is resisting. The formula is:

If 1d100 + 1d101 is less than 102 + MR - the enchantment's power, the enchantment is resisted.

This is sometimes referred to as a "saving throw", after the die-based resistance system employed in Dungeons & Dragons.

Magic resistance saving throw.png

Enchantment power is your spell's power multiplied by a modifier (usually 1) and then passed through a stepdown function which halves your spell power every 30 points above 40. Agony, Pain, Slow, Corona, Teleport Other and all the mass enchantments have modifiers greater than 1. Ensorcelled Hibernation has an additional stepdown.

Resistance Descriptions

Neither the player's nor monster's MR is ever given explicitly, but a rough suggestion of how magic resistant they are can be seen by pressing the @ or % key for the player, and examining a monster's description.

Magic resistance adjectives are as follows:

MR description % screen MR number
not resistant ..... <40
somewhat +.... 40-79
very ++... 80-119
extremely +++.. 120-159
incredibly ++++. 160-199
almost entirely +++++ >=200

As a practical matter, a player who is "incredibly resistant" should be able to usually resist the most dangerous enchanters in the game (such as Kirke, deep elf demonologists, and even ancient liches). More MR will reduce the likelihood of these spells landing even further, but the gains become significantly less important beyond this point.

Player Resistance

Player resistance is determined as below:

Experience level × racial multiplier, plus the following:

Racial multipliers are as follows:

History

Prior to 0.14, when a target resisted a spell, the message would indicate how poorly they fared on that particular resistance roll instead of how difficult in general it is for the target to resist the spell.

Prior to 0.13, Blink Other was subject to magic resistance.