Mutation

Version 0.18: This article may not be up to date for the latest stable release of Crawl.

Mutations are genetic oddities you may receive during your travels in the dungeon. Often acquired at random, they may be helpful or debilitating. This article will discuss types of mutations and ways to gain and lose them. To learn more specifics, see the full list of mutations or read:

• Good mutations
• Bad mutations
• Demonspawn mutations
• Jiyva mutations

Innate and Acquired Mutations

Many species begin the game with mutations in place. Others, like demonspawn and draconians, automatically gain mutations as the game progresses. These innate mutations cannot be resisted or removed, though some can be enhanced by further mutation. For example, a minotaur starts the game with Horns 2, and may reach Horns 3 if further mutated, or a naga might randomly gain another rank of Spit Poison (allowing them to breathe poison clouds).

All other mutations must be acquired through the means outlined below, and can be cured, typically with a potion of mutation. Not all mutations can be acquired randomly; for example, you cannot randomly become a saprovore.

A Note on The Immutable Undead

Undead characters cannot mutate. In situations where a living character would gain a mutation, they either rot or decompose. Decomposition deals temporary damage to your intelligence, dexterity, or strength scores. These will heal back slowly over time as you gain experience, much like draining. Rot permanently shaves points off of your maximum HP. This can be cured by drinking a potion of curing or potion of heal wounds, or by zapping yourself with a wand of healing (rot is healed before HP damage). Since mummies can't drink potions, they can only restore rotten HP with a wand or by using a racial ability they receive at level 13 (costing 1 permanent MP). Ghouls fix rot by eating chunks, so it's not as much of a problem for them.

Viewing Mutations

You can view all of your current mutations by pressing A. In the default settings for the A screen, mutations are displayed in different colors according to type:

• Innate mutations, good or bad, are blue
• Acquired good mutations are light grey
• Acquired bad mutations are red.
• Temporary (also called transient) mutations are light magenta and between brackets.
• Mutations that are a combination of innate and acquired are displayed in cyan or magenta, depending on whether they are good or bad.
• Mutations that are currently suppressed due to a change in form (such as through Spider Form) are dark grey

Gaining Mutations

There are many ways to gain mutations. Although you may want to gain mutations, there are some methods that you should avoid, as they will give you bad mutations most of the time. Zin followers in particular should avoid trying to gain any mutations.

Bad mutations:

• Magic contamination - Whether through a spell miscast, casting certain spells too frequently, stepping on a Zot trap, wielding or wearing ego items or artifacts with the Contamination property, or many other sources, once you have accumulated enough magic contamination you will start glowing. Until this wears off, it has a chance of dealing damage and giving you a mutation each turn. It is weighted towards negative mutations, and ignores half of your mutation resistance.
• Being hit by a mutagenic melee attack - Mnoleg has a mutagenic attack, which has a 25% chance of giving you a bad mutation each time it hits.
• Being hit by Malmutate - The Malmutate spell is the most common source of bad mutations in the game, and can be cast by several monsters (neqoxecs, cacodemons, shining eyes, and orbs of fire).
• You can be temporarily malmutated by the presence of a wretched star. This effect ignores half of your mutation resistance, but fortunately the mutations go away after you earn sufficient additional experience.
• Miscasting a spell - Failing to cast a high-level Transmutations spell (or suffering a miscast from another source, from Xom or Sif Muna for example) has a small chance to give you one or two bad mutations.

Other sources of mutations:

• Some of Xom's actions will mutate you, either bad, (Xom) random, or good depending on its mood.
• A potion of mutation removes 2-4 mutations, then gives 1-3, then one good mutation.
• Eating a mutagenic chunk (the corpse of a guardian naga, shining eye, shapeshifter, glowing shapeshifter, ugly thing, very ugly thing, sky beast, or giant orange brain) may give you one random mutation.
• Some species, notably demonspawn and draconians, gain permanent, useful mutations when leveling up.
• Jiyva offers its own selection of mutations to followers.

Losing Mutations

There are a few ways to lose mutations:

• A potion of mutation removes 2-4 mutations, then gives 1-3, then one good mutation.
• Once per game, followers of Zin with very high piety may get all their mutations removed.
• One possible effect of Zin's wrath is to remove all of your good mutations.
• Miscasting a high-level Transmutation spell. As this could also give you bad mutations, this is not something you should actively try to do.
• Gaining a random mutation. If you're already mutated when you should gain a random mutation, there's a 2% chance per mutation you already have (up to 33%) that you'll lose a mutation instead. This only works with random mutations, not good or bad mutations; god gifts (Xom mainly) have a 67% chance to bypass this test.
• Followers of Jiyva are given the ability to remove random bad mutations.
• Temporary mutations will be lost after obtaining more experience. Resting doesn't work.

Protection Against Mutations

Effects that can cause mutations don't always succeed. Here are all sources of mutation resistance (not cumulative):

• Wearing an artifact with rMut (The Hat of the Alchemist or the Lajatang of Order) will negate 66% of all mutations you gain. This does not apply to potions of beneficial mutation.
• The Mutation Resistance mutation protects you 66.6% of the time at ranks 1 and 2, and 100% at rank 3. Halflings naturally have 1 rank of this mutation.
• Zin's followers have a (Piety/2)% chance to be protected, with 100% resistance at maximum piety. So long as you keep up your piety, this resistance cannot be bypassed, regardless of the mutation source.
• Mummies, ghouls and characters in lich form are "protected" against any form of mutation (they rot instead). Vampires have a chance to rot instead of mutate based on their satiation level:
  • Alive: 0%
  • Very Full: 33%
  • Full: 50%
  • Satiated: 67%
  • Thirsty or less: 100%
    • Potions of beneficial mutation will always succeed for Satiated or better and always fail for Thirsty or worse.
• Characters already heavily mutated may avoid gaining other mutations. Each mutation gives you 6.5% resistance, and each time you resist, there is a 33% chance that you will lose a mutation instead of simply not gaining more. This only works for random mutations, not good or bad mutations.

Exclusive mutations

Not every mutation can be present in a character at once. For starters, several good and bad mutations are direct opposites of each other and are therefore mutually exclusive (Regeneration and Slow healing, Acute Vision and Blurry Vision, Carnivorous and Herbivorous, etc.) Additionally, certain body parts may only have one mutation applied to them, i.e. you can't have both hooves and talons at the same time (by extension, hybrid species like nagas and merfolk can't get either hooves or talons).

There are also certain mutations that are exclusive to certain species. Some of the Demonspawn mutations fall in this category and cannot be obtained by any other species through random mutation. Other mutations like this involve specific body parts that only a few species have (e.g., draconians and gargoyles are the only species who have wings, so only they can receive the Big Wings mutation).

History

• Prior to 0.18, there was an amulet of resist mutation, and rMut from the amulet or from artifacts gave a 90% chance to resist instead of just 66%.

• Prior to 0.16, the Hat of the Alchemist did not grant mutation resistance.

• Prior to 0.13, there were potions of gain strength, dexterity, and intelligence in place of the potion of beneficial mutation.

• Prior to 0.12, Polymorph Other (whether from a wand or the monster version of the spell) could inflict bad mutations on you. It was replaced by Malmutate.