Good mutations

Version 0.30: This article may not be up to date for the latest stable release of Crawl.

This is a list of all of the good mutations which can be acquired. While most of these are useful to any character, some may in fact be significantly detrimental to some builds. Even so, they are included here because "good mutation" is a technical term in the game, not a qualitative judgment. Any of these can be acquired through any source of good mutations, such as a potion of mutation.

Offensive

Some of these mutations will prevent your character from wearing items in certain equipment slots. While this penalty may outweigh the gain your character receives, bear in mind that races which cannot use those slots (ogres, trolls, felids, etc.) lose nothing.

Fangs

Rank	Effect	Flavor
1	Auxiliary bite attack.	You have sharp teeth.
2	Improved auxiliary bite attack.	You have very sharp teeth.
3	Superior auxiliary bite attack.	You have razor-sharp teeth.
Damage: `1 + (2 * rank)` Chance: `40% * (30 + XL)/59` per melee attack Having Acidic Bite adds `4` base damage and `2d4` acid damage. If Vine Stalker, add `XL/3` damage, chance increased to `100% * (30 + XL)/59`, and grants antimagic.
Species notes: Vampires and Felids start with rank 3. Gnolls have rank 1. Vine Stalkers start with rank 2 and upgrade to rank 3 at XL 8.
Good mutation, Demonspawn mutation

Beak

Rank	Effect	Flavor
1	Auxiliary peck attack. Prohibits helmet.	You have a beak for a mouth.
Damage: `6` Chance: `66% * (30 + XL)/60` per melee attack
Species notes: Tengu start with Beak.
Good mutation

Claws

Rank	Effect	Flavor
1	+2 unarmed base damage. Negated by gloves.	You have sharp fingernails.
2	+4 unarmed base damage. Negated by gloves.	You have very sharp fingernails.
3	+6 unarmed base damage. Prohibits gloves.	You have claws for hands.
Using Unarmed Combat with level 3 Claws will decapitate hydra heads.
Species notes: Ghouls start with rank 1 and Trolls start with rank 3. Octopodes cannot gain claws.
Good mutation, Demonspawn mutation

Horns

Rank	Effect	Flavor
1	Auxiliary headbutt attack. Prohibits helmets.	You have a pair of small horns on your head.
2	Improved auxiliary headbutt attack. Prohibits helmets.	You have a pair of horns on your head.
3	Superior auxiliary headbutt attack. Prohibits all headgear.	You have a pair of large horns on your head.
Damage: `5 + (3 * rank)` Chance: `66% * (30 + XL)/59` per melee attack Minotaurs may retaliate against enemies with headbutts.
Species notes: Minotaurs start with rank 2, and Oni start with rank 1. Demonspawn can gain horns as a body slot option. Octopodes cannot gain horns.
Good mutation, Demonspawn mutation

Hooves

Rank	Effect	Flavor
1	Auxiliary kick attack. Negated by boots.	You have large cloven feet.
2	Improved auxiliary kick attack. Negated by boots.	You have hoof-like feet.
3	Superior auxiliary kick attack. Prohibits boots.	You have hooves in place of feet.
Damage: `5 + (5/3 * rank)` Chance: `100% * (30 + XL)/59` per melee attack
Species notes: Demonspawn can gain hooves as a body slot option. Nagas, merfolk, felids, and octopodes cannot gain hooves.
Good mutation, Demonspawn mutation

Talons

Rank	Effect	Flavor
1	Auxiliary kick attack. Negated by boots.	You have sharp toenails.
2	Improved auxiliary kick attack. Negated by boots.	You have razor-sharp toenails.
3	Superior auxiliary kick attack. Prohibits boots.	You have claws for feet.
Species notes: Tengu start at rank 3. Demonspawn can gain talons as a body slot option. Nagas, merfolk, felids, and octopodes cannot gain talons.
Good mutation, Demonspawn mutation

Passive Freeze

Rank	Effect	Flavor
1	When hit in melee, you retaliate with Freeze (1d10, 100% chance).	A frigid envelope surrounds you and freezes all who hurt you.
Prior to 0.27, was a three rank Demonspawn mutation. Rank 1 gave rC+, Rank 2 gave immunity to freezing clouds, and Rank 3 gave passive freeze. Prior to 0.15, Rank 1 granted potion conservation, and rank 2 granted rC+.
Good mutation

MP-Powered Wands

Rank	Effect	Flavor
1	Automatically boosts wands, using 3 MP per zap.	You expend magic power (3 MP) to strengthen your wands.
Boosts the power of your wands by 33%. If you don't have enough MP, you'll use the wand unboosted.
Good mutation

Defensive

Shaggy Fur

Rank	Effect	Flavor
1	+1 AC	You are covered in fur.
2	+2 AC	You are covered in thick fur.
3	+3 AC, rC+	Your thick and shaggy fur keeps you warm.
Species notes: Trolls and felids start at rank 1; felids gain rank 2 at XL 6 and rank 3 at XL 12.
Good mutation

Camouflage

Rank	Effect	Flavor
1	+40 Stealth	Your skin changes colour to match your surroundings.
2	+80 Stealth	Your skin blends seamlessly with your surroundings.
3	+120 Stealth	Your skin perfectly mimics your surroundings.
Species notes: Octopodes start at rank 1.
Good mutation

Resistances

Fire Resistance

Rank	Effect	Flavor
1	rF+	Your flesh is heat resistant.
2	rF++	Your flesh is very heat resistant.
3	rF+++	Your flesh is almost immune to the effects of heat.
Species notes: Red draconians develop rank 1 upon changing color.
Good mutation

Cold Resistance

Rank	Effect	Flavor
1	rC+	Your flesh is cold resistant.
2	rC++	Your flesh is very cold resistant.
3	rC+++	Your flesh is almost immune to the effects of cold.
Species notes: White draconians develop rank 1 upon changing color.
Good mutation

Electricity Resistance

Rank	Effect	Flavor
1	rElec	You are resistant to electric shocks.
Species notes: Gargoyles start with rank 1. Black draconians develop rank 1 upon changing color.
Good mutation

Poison Resistance

Rank	Effect	Flavor
1	rPois	Your system is resistant to poisons.
Species notes: Nagas start with rank 1. Green draconians develop rank 1 upon changing color. Gargoyles are instead immune to poison.
Good mutation

Strong-Willed

Rank	Effect	Flavor
1	Willpower+	You are resistant to hostile enchantments.
2	Willpower++	You are highly resistant to hostile enchantments.
3	Willpower+++	You are extremely resistant to the effects of hostile enchantments.
Good mutation

Clarity

Rank	Effect	Flavor
1	Clarity	You possess an exceptional clarity of mind.
Good mutation

Mutation Resistance

Rank	Effect	Flavor
1	66.6% resistance to further mutation (50% for transient mutations).	You are somewhat resistant to further mutation.
2	66.6% resistance to further mutation (50% for transient mutations). Mutation removal fails 50%.	You are somewhat resistant to both further mutation and mutation removal.
3	100% resistance to further mutation. Mutation removal fails 100%.	You are almost entirely resistant to both further mutation and mutation removal.
This mutation stacks with other sources of mutation protection such as Zin and the hat of the Alchemist multiplicatively. Rank 3 of the mutation can only be removed by Jiyva, Xom (retribution or not), Zin (retribution), or by magical contamination.
Species notes: Prior to their 0.27 removal, Halflings started at rank 1.
Good mutation

Perception

Acute Vision

Rank	Effect	Flavor
1	Grants see invisible.	You have supernaturally acute eyesight.
Species notes: Nagas, spriggans, vampires, and felids start with this.
Good mutation

Antennae

Rank	Effect	Flavor
1	Shows the location of all invisible enemies in line of sight. Detects all monsters within 3 tiles, even through walls or opaque clouds. Prohibits helmets.	You have a pair of small antennae on your head.
2	Range increases to 5 tiles. Prohibits helmets.	You have a pair of antennae on your head.
3	Range increases to 7 tiles. Grants see invisible. Prohibits all headgear.	You have a pair of large antennae on your head.
When playing in console mode, creatures not in line of sight are revealed as { or { glyphs, depending on whether the entity is hostile or friendly. In tile mode, they appear as icons which similarly indicate hostility. Mimics will be identified as soon as they enter your antennae range.
Species notes: Formicids start with rank 3. Demonspawn can gain antennae as a body slot option.
Good mutation, Demonspawn mutation

Sense Surroundings

Rank	Effect	Flavor
1	Reveal random tiles outside LOS	You passively map a small area around you.
2	Reveal more random tiles outside LOS	You passively map the area around you.
3	Reveal many random tiles outside LOS	You passively map a large area around you.
Good mutation

General

Evolution

Rank	Effect	Flavor
1	Gain mutations until trait expires.	You have hidden genetic potential.
2	Same as previous level, though lasts longer.	You have great hidden genetic potential.
Triggers about once per XL, providing another good mutation. Every two activations, it reduces its level by one. Changed in 0.28, see the Evolution page for more details.
Good mutation

Wild Magic

Rank	Effect	Flavor
1	Spell Power+, Spell Success-	Your spells are a little harder to cast, but a little more powerful.
2	Spell Power++, Spell Success--	Your spells are harder to cast, but more powerful.
3	Spell Power+++, Spell Success---	Your spells are much harder to cast, but much more powerful.
Each level gives +30% (additively stacked, then multiplied) to raw spellpower and +4% (additive) to raw spell failure rate. Generally, you will get less than +30% actual power. You will get less than +4% failure if your failure is already low (< 8%), but slightly more if your failure is high.
Good mutation

Improved Attributes

Rank	Effect	Flavor
1	+4 to STR, INT or DEX -1 to the other two stats.	Your muscles are strong. Your mind is acute. You are agile.
2	+8 to STR, INT or DEX -2 to the other stats	Your muscles are very strong. Your mind is very acute. You are very agile.
It's possible to gain this mutation for multiple different stats, but each stat may have up to 2 levels.
Good mutation

Regeneration

Rank	Effect	Flavor
1	HP regeneration rate +0.8 HP/turn	Your natural rate of healing is unusually fast.
2	HP regeneration rate +1.6 HP/turn	You heal very quickly.
3	HP regeneration rate +2.4 HP/turn	You regenerate.
Each level healed 1 HP/turn in 0.27, and 0.4HP/turn prior. Excludes Slow Metabolism prior to 0.26.
Species notes: Trolls and Vine Stalkers start at rank 1.
Good mutation

Robust

Rank	Effect	Flavor
1	+10% max HP	You are robust.
2	+20% max HP	You are very robust.
3	+30% max HP	You are extremely robust.
Good mutation, Demonspawn mutation

High MP

Rank	Effect	Flavor
1	+10% max MP	You have an increased reservoir of magic.
2	+20% max MP	You have a considerably increased reservoir of magic.
3	+30% max MP	You have a greatly increased reservoir of magic.
Species notes: Demigods start at rank 1.
Good mutation

Scales

As they level, non-"monstrous" demonspawn naturally receive three ranks of a single scales mutation; other sources of mutation will only give the scales they would get naturally. Draconians have natural scales independent of these mutations, and are unable to gain other scales. Currently only checked for iridescent scales, this may be a bug.

Iridescent Scales

Rank	Effect	Flavor
1	+2 AC	You are partially covered in iridescent scales.
2	+4 AC	You are mostly covered in iridescent scales.
3	+6 AC	You are completely covered in iridescent scales.
Good mutation

Large Bone Plates

Rank	Effect	Flavor
1	+4 SH	You are partially covered in large bone plates.
2	+6 SH	You are mostly covered in large bone plates.
3	+8 SH	You are completely covered in large bone plates.
Good mutation, Demonspawn mutation

Thin Skeletal Structure

Rank	Effect	Flavor
1	+2 DEX, +25 Stealth	You have a somewhat thin skeletal structure.
2	+4 DEX, +50 Stealth	You have a moderately thin skeletal structure.
3	+6 DEX, +75 Stealth	You have an unnaturally thin skeletal structure.
Good mutation, Demonspawn mutation
In earlier versions of Crawl, this mutation also reduced strength by 1 per rank.

Sturdy Frame

Rank	Effect	Flavor
1	-2 Encumbrance from equipped armour.	Your movements are slightly less encumbered by armour. (ER -2)
2	-4 Encumbrance from equipped armour.	Your movements are less encumbered by armour. (ER -4)
3	-6 Encumbrance from equipped armour.	Your movements are significantly less encumbered by armour. (ER -6)
This mutation allows the player to wear heavier Armour without the associated penalties to EV or Spell Success.
Good mutation, Demonspawn mutation

Species exclusive

These mutations may only be acquired by certain species. Does not include demonspawn mutations, and only includes mutations that can be acquired/improved randomly.

Spit Poison

Rank	Effect	Flavor
1	Grants the Spit Poison ability.	You can spit poison.
2	Upgrades to Breathe Poison.	You can exhale a cloud of poison.
Species notes: Exclusve to Nagas, who start at level 1.
Good mutation

Stinger

Rank	Effect	Flavor
1	Adds damage and Venom to auxiliary tail slap.	Your tail ends in a poisonous barb.
2	Adds more damage to auxiliary tail slap.	Your tail ends in a sharp poisonous barb.
3	Adds most damage to auxiliary tail slap.	Your tail ends in a wickedly sharp and poisonous barb.
Damage: `6 + (4 if you have Armoured Tail) + (2 * rank)` Chance: `50% * (30 + XL)/59` per melee attack
Species notes: Exclusive to Nagas, Armataurs, and Draconians, who can get this randomly. Green draconians gain rank 1 at XL14 (and may gain more).
Good mutation

Big Wings

Rank	Effect	Flavor
1	You now fly permanently.	You have big, strong wings, capable of bearing you through the air.
Prior to 0.27, flight could be toggled on or off. Prior to 0.17, the flight granted by this mutation was temporary if it wasn't from your species.
Species notes: Exclusive to draconians and gargoyles. Black draconians and gargoyles naturally develop it at XL 14, though other draconians can acquire it as a random mutation.
Good mutation

Tentacle Spike

Rank	Effect	Flavor
1	Adds damage to auxiliary tentacle slap.	One of your tentacles bears a spike.
2	Adds more damage to auxiliary tentacle slap.	One of your tentacles bears a nasty spike.
3	Adds most damage to auxiliary tentacle slap.	One of your tentacles bears a large vicious spike.
Damage: `5 + rank` Chance: `100% * (30 + XL)/59` per melee attack
Species notes: Exclusive to octopodes. Octopodes may also temporarily induce rank 3 of this mutation with Beastly Appendage.
Good mutation

History

In 0.33, three new good mutations will be added: Efficient Magic, Ephemeral Shield, and Time-Warped Blood.
Prior to 0.27, you could obtain many different scale mutations; there was a hard limit of 3 levels (of any combination of scale mutation) at a time. Blink (mutation) was removed, Noise Dampening was added.
Prior to 0.14 the Fast mutation was available as a random mutation and the Antennae mutation did not show invisible enemy indicators outside range 3 & 5 at ranks 1 & 2.
In 0.13, the Teleport Control, Strong Stiff, and Flexible Weak mutations were removed, and Improved Attributes was changed to only have 2 levels, each of which granted +2 to an attribute.