Passive attack

Some monsters possess a passive attack - it is used automatically in retaliation to a melee attack against the monster. They can be avoided by use of ranged weapons, pounding with a polearm or lance, or being resistant to the attack. Passive attacks are not affected by magic cancellation.

The most infamous example of such a passive attack is the floating eye's paralysis gaze - hitting a floating eye normally paralyses the player for a period of time, during which they are vulnerable to outside attack - a cause of numerous YASDs. Other well-known examples include the various jellies, puddings, molds and acid blobs.

A passive attack is denoted by AT_NONE in the source code.

List of passive attacks

Passive attacks against the player are handled in uhitm.c:passive(). Monsters have at most 1 passive attack, which is defined separately from any other attacks they might have.

Acid

b acid blob, j spotted jelly, j ochre jelly, F green mold

• 50% chance of an acid damage. If this succeeds, there's a 1/30 chance that your armor is subject to corrosion
• 1/6 chance, independent of the above, that whatever you attacked with (boot, weapon, etc) is subject to erosion
• Your strength is abused

Stoning

c chickatrice, c cockatrice

• If you hit with a bare appendage, you turn to stone and die instantly (unless stoning resistant)

Rust

R rust monster

• If the monster is cancelled, nothing happens
• If you kicked it, your boots suffer the effects of a rust trap
• Otherwise, 1/6 chance that your weapon/gloves are subject to rust

Corrosion

P black pudding

• Exactly like the rust attack above, but with the more-powerful corrosion effect

Magic missile

@ Oracle (the source code comment is "wrath of gods for attacking Oracle")

• If you have magic resistance, no effect
• Else, you are hit with a magic missile attack

Drain enchantment

R disenchanter

• If the monster is canceled, nothing happens
• If you attacked with an enchanted weapon/boots/gloves, they lose 1 enchantment. Artifact weapons resist the drain 90% of the time, and ordinary equipment resists 10% of the time.

Paralysis

b gelatinous cube, e floating eye

• If the monster is canceled or dies from the blow, nothing happens
• If you have free action, "You momentarily stiffen"
• If it is a floating eye and you have reflection, you cannot see it, or it is blind, nothing happens
• Else, there is a 2/3 chance that you will be paralyzed
• Being frozen by a gelatinous cube abuses dexterity

Cold

j blue jelly, F brown mold

• If the monster is canceled or dies from the blow, or if you are cold resistant, nothing happens
• Else, there is a 2/3 chance that you suffer a cold attack
• The monster gains half its attack damage in HP, possibly increasing its max HP
• If the monster's max HP is now high enough, it reproduces

The self-healing makes blue jellies especially deadly to lower-level characters who can't reliably hit hard enough to offset the healing.

Stunning

F yellow mold

• If the monster is canceled or dies from the blow, nothing happens
• 2/3 chance that you become stunned

Fire

v fire vortex, E fire elemental, F red mold

• If the monster is canceled or dies from the blow, or if you are fire resistant nothing happens
• 2/3 chance of fire damage
• If you are polymorphed into an iron golem, you heal by the damage amount, instead

Electricity

v energy vortex

• If the monster is canceled or dies from the blow, or if you are shock resistant nothing happens
• 2/3 chance of shock damage
• If you are polymorphed into a flesh golem, you heal by 1/6 of the damage amount, instead (a reference to Frankenstein's Monster)

Sticky

m large mimic, m giant mimic

• If you walk into the mimic without knowing that there is a monster there, you are affected by their sticking attack, and cannot move away.

Slime

• Although the green slime has a passive slime attack defined, there is no code to handle it.

Source code references