Mutation

Version 0.12: This article may not be up to date for the latest stable release of Crawl.

For a list of mutations, see List of mutations

Mutations are genetic oddities you may receive during your travels in the dungeon. They come in many varieties, ranging from the very good (e.g. electricity resistance, the ability to breathe fire) to the very bad (teleportitis, deteriorating body). A complete list can be found among the various List of mutations pages.

Undead characters cannot mutate. In situations where a living character would gain a mutation, they either rot or decompose instead. Decomposition means temporarily losing a point of Intelligence, Dexterity, or Strength. This will heal back after a long time (it will heal randomly, one stat at a time) or can be fixed by quaffing a potion of restore abilities or eating a royal jelly. It can also mean that they rot, permanently losing points off their max HP. This can be fixed by drinking a healing or heal wounds potion or zapping oneself with a wand of healing while already fully healed. Since mummies can't drink potions, they can only restore rotten HP with a racial ability they receive at level 13 (costs 1 permanent MP) or a wand of healing at full HP. Ghouls rot all the time and can restore themselves by eating chunks, so it's not as much of a problem for them.

Innate vs. Acquired Mutations

There are two kinds of mutations in the game: acquired and innate. Acquired mutations are gained through the various means outlined below, and can be cured, usually with a potion of cure mutation. Innate mutations are the characteristics of a species and cannot be removed by any means. Innate mutation examples include a Spriggan's ability to see invisible or a Naga's poison spit. While most species start with all the innate mutations they will ever have, some, most notably Demonspawn, gain them as they level up. Mutation resistance has absolutely no effect on this whatsoever, and as previously mentioned, they cannot be removed. However, such mutations can be "expanded" by acquired mutations: for example, a naga might randomly gain another rank of poison spit (allowing them to breath poison clouds), or a minotaur's horns might expand to become large horns, precluding caps altogether. Note that not all innate mutations can be acquired randomly; for example, you cannot randomly become a saprovore.

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 grey
• Acquired bad mutations are red.
• 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 should avoid trying to gain any mutation.

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 MUT 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 giving you a mutation each turn. It is weighted towards negative mutations, and will often bypass mutation resistance.
• Being hit by a mutagenic melee attack - Mnoleg and pulsating lumps have mutagenic attacks with a 25% chance of giving a bad mutation each time they hit.
• Being hit by Malmutate - Beams of Malmutate can be generated by several monsters (neqoxecs, cacodemons, shining eyes, orbs of fire). You can also be temporarily malmutated by the presence of a wretched star There's no magic resistance check here, only resist mutation, so be very careful when encountering one of these monsters.
• Miscasting a spell - Failing to cast a high-level transmutation 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.
• Mutagenic fog - Getting caught in mutagenic fog may grant you mutations each turn you remain inside it, but they're weighted toward bad ones.

Other sources of mutations:

• Drawing the "Helix" card from a deck of Wonders or Changes may give you a random or a good mutation.
• Some of Xom's actions will mutate you, either bad, (Xom) random, or good depending on its mood.
• Quaffing a potion of gain DEX/INT/STR gives 1 level in the corresponding mutation.
• A potion of mutation gives up to 3 random mutations.
• Eating a mutagenic chunk - The corpse of a guardian naga, shining eye, great orb of eyes, shapeshifter, glowing shapeshifter, ugly thing, very ugly thing, sky beast, or giant orange brain will give you one random mutation. If the corpse is rotten, the mutation will be heavily weighted towards the bad ones.
• 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:

• Drinking a potion of cure mutation. This is the main way to get rid of unwanted mutations.
• Drawing the Helix card from a deck of Wonders or Changes may delete a random or a bad mutation.
• Once per game, followers of Zin with very high piety may get all their mutations removed. On the other hand, one possible effect of Zin's wrath is to remove all 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 can use an invocation to remove random bad mutations.

Protection Against Mutations

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

• An amulet of resist mutation will negate 90% of all mutations you gain (nothing happens instead). This does not apply to potions of Gain Dexterity/Intelligence/Strength.
• The Mutation Resistance mutation protects you 66.6% of the time at ranks 1 and 2, and 100% at rank 3.
• Zin's followers have a (Piety/2)% chance to be protected, with 100% resistance at ****** piety. This does not apply to potions of Gain Dexterity/Intelligence/Strength.
• Mummies, ghouls and characters in lich form are protected against any form of mutation (they rot instead). Vampires have a chance to rot based on their satiation level:
  • Alive: 0%
  • Very Full: 33%
  • Full: 50%
  • Satiated: 67%
  • Thirsty or less: 100%
    • Potions of gain strength/dexterity/intelligence 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 a start, 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 ones who have wings, so only they can receive the Big Wings mutation).

History

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.