Bad mutations

Here is a list of all the bad mutations you can acquire. Although some may have situational uses, they are at best mixed blessings. Any of these can be acquired through any source of bad mutations.

Offensive

Berserk

Rank	Effect	Flavor
1	1% chance of berserking each time you attack. Reduces chance of passing out afterwards to 3%.	You tend to lose your temper in combat.
2	Same, with a 3% chance of berserking and 2% chance of passing out.	You often lose your temper in combat.
3	Same, with a 9% chance of berserking and 1.5% chance of passing out.	You have an uncontrollable temper.
Often referred to as "berserkitis", Clarity or "Near Starving" hunger negates this.
Formicids are exempt, because their stasis stops them from berserking.
Bad mutation

Defensive

Deformed

Rank	Effect	Flavor
1	Reduces body armour base AC by half.	Armour fits poorly on your strangely shaped body.
Does not stack with Jiyva's Pseudopods mutation. Does not affect AC from any other source (i.e. other equipment, the protection ego, etc.). Bonus AC from your Armour skill is still calculated based on the armour's full base AC.
Species notes: Nagas and Centaurs start with this mutation. Draconians, octopodes and felids cannot gain this mutation as they cannot wear body armour.
Bad mutation

Scream

Rank	Effect	Flavor
1	Chance to shout when enemies enter line of sight (same noise as tt).	You occasionally shout uncontrollably at your foes.
2	Greater chance for louder shouts.	You sometimes yell uncontrollably at your foes.
3	Greatest chance for loudest shouts.	You frequently scream uncontrollably at your foes.
Bad mutation

Movement

Slow

Rank	Effect	Flavor
1	Movement delay * 1.2	You cover ground slowly.
2	Movement delay * 1.44	You cover ground very slowly.
3	Movement delay * 1.728	You cover ground extremely slowly.
Does not affect your alternate forms. Only occurs as a starting mutation, i.e. does not occur randomly.
Species notes: Nagas start at rank 2.
Bad mutation

Teleport

Rank	Effect	Flavor
1	You are sometimes teleported next to a monster a short distance away from you.	You are occasionally teleported next to monsters.
2	More frequent and can be teleported longer distances.	You are sometimes teleported next to monsters.
3	Most frequent and can be teleported to anywhere on the floor.	You are often teleported next to monsters.
Formicids are exempt, because they cannot teleport.
Bad mutation

Perception

Blurry Vision

Rank	Effect	Flavor
1	+5 auts to read scrolls.	Scrolls take you a little longer to read.
2	+10 auts to read scrolls.	Scrolls take you longer to read.
3	+20 auts to read scrolls.	Scrolls take you much longer to read.
Note that the normal 10 aut delay to read a scroll still applies. Specifically, reading a scroll involves first the penalty from blurry vision, then the scroll takes effect, then the normal 10 aut delay for reading the scroll occurs.
Prior to 0.16, this mutation gave a 20%/40%/60% chance to fail all attempts to read books or scrolls.
Bad mutation

Diet

Herbivorous

Rank	Effect	Flavor
1	Chunks inedible, rations provide less nutrition.	You are a herbivore.
Species notes: Spriggans start at rank 1.
Prior to 0.21, this mutation had three levels. Prior to 0.15, characters could become partially or completely herbivorous through mutations.
Bad mutation

Fast Metabolism

Rank	Effect	Flavor
1	Nutrition cost of all actions +1	You have a fast metabolism.
2	Nutrition cost of all actions +2	You have a very fast metabolism.
3	Nutrition cost of all actions +3	Your metabolism is lightning-fast.
Species notes: Trolls start at rank 3 (and also have a further, species-specific hunger cost).
Bad mutation

General

Deterioration

Rank	Effect	Flavor
1	A small chance for stat loss whenever you take damage.	Your body sometimes deteriorates on taking damage.
2	Increased chance for stat loss.	Your body often deteriorates on taking damage.
Bad mutation

Frail

Rank	Effect	Flavor
1	Max HP -10%	You are frail.
2	Max HP -20%	You are very frail.
3	Max HP -30%	You are extremely frail.
Bad mutation

Low MP

Rank	Effect	Flavor
1	Max MP -10%	Your magical capacity is low.
2	Max MP -20%	Your magical capacity is very low.
3	Max MP -30%	Your magical capacity is extremely low.
Bad mutation

Reduced Attributes

Rank	Effect	Flavor
1	-2 to STR, INT or DEX	You are weak You are dopey. You are clumsy.
2	-4 to STR, INT or DEX	You are very weak You are very dopey. You are very clumsy.
While it's possible to gain this mutation multiple times, each attribute is limited to 2 ranks.
Bad mutation

Slow Healing

Rank	Effect	Flavor
1	No (non-divine) HP regeneration when monsters are in line of sight.	You do not regenerate when monsters are visible.
Species notes: Ghouls start at rank 1.
The regeneration spell will not function when this mutation is active, however Trog's Hand will. Prior to 0.20, this mutation was called slow regeneration, and it had 3 ranks: at rank 1, regeneration was slowed when monsters were visible, rank 2 was the current rank 1, and at rank 3 regeneration was completely stopped. Prior to 0.17, this mutation was called slow healing.
Bad mutation

See Also

• Good mutations
• Demonspawn mutations
• Jiyva mutations

History

In 0.13 Reduced Attributes was changed to only have two levels, each of which gives you -2 to an attribute.