Cloud

Version 0.22: This article may not be up to date for the latest stable release of Crawl.

Clouds are temporary dungeon features which occupy tiles. They usually cause damage or status effects to anything which occupies the tiles they are in, though some of them do nothing more than block LOS. They come in a variety of elemental flavors, can be created in many different ways, and can be potent weapons if handled properly. Clouds will dissipate on their own in time, but some areas will perpetually generate new clouds. Regardless of the type of cloud, player-generated clouds cannot be placed outside of LOS and will dissipate instantly should the player move away from them. Additionally, no clouds can be placed on tiles where a cloud already exists; players may make use of this by, for example, casting Freezing Cloud near themselves while standing in a cloud of smoke.

Regardless of other properties, players that follow Qazlal or wear a scarf of cloud immunity are immune to the harmful effects of all clouds.

Cloud Varieties

Atmospheric

Atmospheric clouds are merely decorative and have no other effect, though no other clouds may be generated on top of them. Several varieties of atmospheric clouds exist, such as sparse dust, thin mist, or magical condensation.

Atmospheric clouds are largely created by the dungeon level around you or as part of a vault; the Swamp, for example, constantly generates clouds of thin mist. Certain other effects may make atmospheric clouds, such as the clouds of dust left behind by jumping spiders or trails of magical condensation left in the wake of worshipers of Xom.

Opaque

Opaque clouds partially block line of sight; your LOS stops after two opaque clouds in any direction. Other than potentially blocking your view, opaque clouds have no other effect. Like atmospheric clouds, there are multiple varieties of opaque clouds, including several colours of smoke, translocational energy, golden dust, salt, white fluffiness, and ink.

Opaque clouds are somewhat rarer than atmospheric clouds, but may still be generated by the dungeon or certain vaults (pools of lava and altars to Dithmenos commonly have black smoke around them). You can generate clouds of smoke by reading a scroll of fog, using the Cloak of the Thief or with Dithmenos's Bleed Smoke trait, and any creature will leave behind a cloud of translocational energy when it blinks, teleports, or is banished. Followers in good standing with the Wu Jian Council create clouds of golden dust when using their Heavenly Storm ability. Multiple areas in the Desolation of Salt and Cloud Mages' Chambers constantly generate clouds of salt and white fluffiness, respectively, and krakens may release a cloud of ink when injured.

Calcifying dust

Clouds of calcifying dust are another variety of opaque cloud that blocks LOS, but they are far more dangerous than mere smoke or fog. Any creature that stands in calcifying dust begins to petrify, gradually turning into a helpless statue for several turns. Fortunately, players are only affected by these clouds if you end your turn in them; if you move out of the clouds as soon as they appear, you'll be fine (though this may make it hard to fight back).

Catoblepae can belch forth clouds of calcifying dust at their prey, affecting friend and foe alike.

Steam

Steam clouds are tiles full of scaldingly hot mist. These are opaque and block LOS, but will also deal small amounts of damage to anything that does not have resistance to steam or fire.

Any area that has lava exposed to water will emit an endless amount of steam. You can create steam yourself by using Fire Magic over water, Ice Magic over lava, or with a pale draconian's breath attack.

• Damage per turn: (3d16)/3 (affected by steam resistance and/or fire resistance)

Flame

Clouds of flame are tiles which have caught on fire, dealing fire damage to anything standing in them. Firing some Ice Magic spells (Throw Frost, Bolt of Cold) through them will put them out. Demonspawn with 2 ranks of fire-themed mutations (Ignite Blood and Hurl Hellfire) become immune to flame clouds.

Clouds of flame can be created by using the spells Conjure Flame, Ignite Poison (when poison clouds are present), and Fire Storm, a wand of clouds, a red draconian's breath attack, being a demonspawn with Ignite Blood 3, being a worshiper of Qazlal, and by igniting bushes or trees with powerful Fire Magic.

• Damage per turn: 10 + (3d23)/3 to the player; 6 + (3d16)/3 to monsters (affected by fire resistance)

Spreading flames

Spreading flames are a special type of flame cloud created when trees catch fire from powerful Fire Magic or bolts of lightning. They act much like regular flames, but periodically create new flames in tiles next to them; if any trees are in these tiles, they may also catch fire, continuing the cycle until the fires eventually burn out.

Freezing vapour

Freezing clouds are tiles filled with brutally cold mist. They function almost identically to flame clouds, except that they deal cold damage and they don't have any effects on trees. Demonspawn with 2 ranks of ice-themed mutations (Icemail and Passive Freeze) become immune to freezing vapour.

They can be created with a wand of clouds, the Freezing Cloud and Glaciate spells, by using powerful Ice Magic over a body of water, or by destroying a simulacrum. Miscasting some Ice Magic spells can also create clouds of freezing vapour.

• Damage per turn: 10 + (3d23)/3 to the player; 6 + (3d16)/3 to monsters (affected by cold resistance)

Noxious fumes

Clouds of noxious fumes (also known as mephitic clouds) are composed of mildly toxic and foul-smelling gases. Anything caught in one takes minor poison damage and is confused for several turns; creatures with more HD are less likely to be confused.

The most common sources are the Mephitic Cloud spell and the breath attacks of swamp drakes and green draconians, although they can also be created by some miscast effects.

• Damage per turn: (3d3)/3 (poison resistance gives immunity to all effects)

Poison

Poison clouds are tiles filled with highly poisonous gas. Anything caught in one will take damage and be poisoned, though poison resistance renders creatures immune. For even more damage, use the Ignite Poison spell to immediately convert these into flame clouds!

Players can create a single, extremely short-lived cloud with the Poisonous Vapours spell, although some miscasts can also create them. Swamp dragons, gold dragons, enemy green draconians, and green deaths breathe these, as can player nagas with the appropriate mutation.

• Damage per turn: (3d10)/3 (poison resistance gives immunity)

Miasma

Miasma (also known as foul pestilence) clouds are extremely dangerous banks of corrupt fog. Anything caught in one will take damage, rot, and become slowed and poisoned. If you can create them, they are extremely useful in combat so long as you don't catch yourself by accident.

Miasma clouds appear in some vaults, including the undead version of Swamp:5. You can create them with the Corpse Rot spell or the Foul Stench demonspawn mutation, and death drakes and ushabtiu will breathe them at you.

• Damage per turn: (3d12)/3 (rotting resistance gives complete immunity, poison resistance stops you from being poisoned, and stasis prevents you from being slowed; Zin's Vitalisation protects you from everything but the damage)

Spectral flames

Spectral flames burn with the chill fires of undeath. They deal partially-irresistible negative energy damage (though the undead are entirely immune) and occasionally summon spectral things that immediately attack creatures hostile to their creator.

Spectral flames are only ever created by monsters: ghost crabs and revenants can both create banks of spectral fire.

• Damage per turn: 4 + (3d14)/3 (partially affected by negative energy resistance; undead are immune)

Negative energy

Clouds of negative energy are charged with dangerous soul-sapping forces. They deal large amounts of negative energy damage to creatures unfortunate enough to be caught in them as well as inflicting the drained condition. Of course, creatures that are immune to the effects of negative energies (such as plants, demons, and the undead) may safely ignore these clouds.

Players may create negative energy clouds with a wand of clouds at moderate power (at least 6 Evocations).

• Damage per turn: 10 + (3d23)/3 to the player; 6 + (3d16)/3 to monsters (affected by negative energy resistance)

Acidic fog

Acidic fog is a hideously dangerous type of cloud; made of corrosive acid, it swiftly dissolves anything caught in it, though monsters that resist acid are immune. Fortunately, these creatures are few and far between, making it an effective weapon virtually anywhere outside of the Slime Pits.

Acidic fog can only be created with a wand of clouds at high power (requires at least 14 Evocations).

• Damage per turn: 10 + (3d23)/3 to the player; 6 + (3d16)/3 to monsters (affected by corrosion resistance)

Blessed fire

Clouds of blessed fire burn with holy, cleansing light. They are opaque and block LOS, and are particularly deadly to forces of evil such as demons and the undead (more mundane mortals still burn, but to a lesser degree). Only creatures consecrated by or in service to the good gods are immune to their effects.

Clouds of blessed fire are extremely rare, only naturally appearing in a very few vaults. Certain powerful holy creatures may create blessed flames to hinder their foes, however.

• Damage per turn: 8 + (3d19)/3 to the player; 4 + (3d12)/3 to monsters (affected by holy resistance)

Mutagenic fog

Mutagenic fog is clouds of raw, uncontrolled magic. Stepping in these clouds will inflict heavy magical contamination upon a player which, if left unchecked, will likely cause bad mutations and possibly even damaging explosions. Monsters which enter the clouds are instead polymorphed each turn they spend in the fog.

These clouds are usually only found in vaults. Cigotuvi's Fleshworks in particular has several rooms filled with mutagenic fog.

Seething Chaos

Formed from the unpredictable forces of pure chaos, clouds of seething chaos produce effects similar to being hit with a weapon of chaos on any creature that enters them.

Clouds of chaos are generally only seen when destroying a chaos spawn or as the breath weapon of apocalypse crabs.

Rain

Rain clouds will create water over time on their tiles. Solid ground becomes shallow water, and shallow water becomes deep water. However, this extra water is short-lived and will evaporate soon, returning the floor to its normal state. Creatures made entirely of fire such as fire elementals or efreet will also take damage from the rainfall.

Sky beasts may create rain when turning invisible or becoming visible again, and players wearing the Robe of Clouds generate rain around themselves. Followers of Fedhas Madash, however, may use its Rain ability to permanently create pools of water.

• Damage per turn: (3d9)/3 (only applies to fiery monsters)

Thunder

Thunder clouds are somewhat unusual in that they only occasionally deal damage. Every so often, lightning will strike the ground beneath a cloud of thunder, dealing heavy lightning damage and making a great deal of noise. Much like rain clouds, thunder clouds produce enough rain to damage fiery creatures beneath them, though they never make enough to leave pools of water on the floor.

Thunder clouds can be created with a wand of clouds at medium power (at least 10 Evocations). They also periodically generate around worshipers of Qazlal.

• Damage per turn: (3d9)/3 (only applies to fiery monsters)
• Damage per lightning strike: (affected by electricity resistance)

Raging winds

Clouds of raging winds are created by tornadoes, whether from a player casting the spell or the presence of an air elemental, twister, or diamond obelisk. They deal heavy physical damage to creatures caught in them (damage increases as creatures approach the eye of the storm) as well as lifting them into the air and moving them in a circle around the caster. Additionally, most tornadoes are capable of blowing down trees (though an air elemental's Vortex is too weak to do so).

• Damage per turn: (creatures with are immune)

History

• Prior to 0.15, clouds of mutagenic fog directly caused mutations rather than causing heavy magical contamination.
• Prior to 0.14, clouds could be placed outside of the caster's LOS and dissipated slower outside of LOS. 0.14 also added clouds of negative energy, thunder, and acid.
• 0.13 added spectral flames.