Mutation

Version 0.28: 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 they level up. These innate mutations cannot be resisted or removed, though some can be enhanced by further mutation. For example, a minotaur's Horns 2 may lengthen into Horns 3.

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 fast.

Undead characters cannot mutate. In situations where a living character would gain a mutation, the undead suffer stat drain, which can be cured by gaining XP.

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 intentionally mutating, but with increasing piety become immune to involuntary mutation.

Random Mutation:

• Some of Xom's actions will mutate you, either bad, (Xom) random, or good depending on its mood.
• A potion of mutation removes 2-3 mutations, then gives 1-3, weighted towards good mutations.
• Some species, notably demonspawn and draconians, gain permanent, useful mutations when leveling up.
• Jiyva offers many, including its own selection of mutations to followers.

Bad mutations:
These sources have an 80% chance to give you a bad mutation, and a 20% chance for a random one.

• 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 ignores half of your mutation resistance.
• 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 Hell's mystical force or 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.
• 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.
• 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.

Losing Mutations

There are a few ways to lose mutations:

• A potion of mutation removes 2-3 mutations, then gives 1-3.
  • Followers of Zin may drink potions of mutation at ****** (160) piety to remove mutations; there's no chance to gain mutations, so there's no hit to piety.
• One possible effect of Zin's wrath is to remove all of your good mutations.
• Jiyva has a 25% chance to remove a mutation level per mutation, doubled if its a bad mutation, whenever it gifts new ones.
• 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.
• Temporary mutations are lost after obtaining more experience.

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.
• 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/1.6)% chance to be protected, with 100% resistance at 6*. 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 experience stat drain instead).
• 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 Inhibited Regeneration, Robust and Frail, 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 0.28, Jiyva had the ability to Cure Bad Mutations. Its mutation gifting logic was also changed between versions.
• Prior to 0.21, random mutations could be obtained by eating mutagenic chunks.
• In 0.20, potions of cure mutation, beneficial mutation, and mutation were merged.
• Prior to 0.20, undead would sometimes rot instead of taking stat damage in place of mutations, and Mummies had a self-restoration ability.
• 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 0.15, vampires had differing responses to mutations at different satiation levels.
• 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.