Cloudkill — Poisonous Fog Spell Rules
Conjuration · Poisonous mist · Moving battlefield hazard
Yellow-green vapour spills down the steps of a city gate and fills the street. The guards can hear the bells but cannot see the warning flags. The cloud drifts onward, leaving the survivors to choose between the enemy at their backs and the poisonous fog ahead.
At a Glance
| Spell | Cloudkill |
|---|---|
| D&D 2024 | Level 5 Conjuration, 5d8 Poison damage with Constitution save; once per turn |
| D&D 2014 | 5th-level Conjuration, 5d8 poison damage; save on entering or starting turn inside |
| Pathfinder 1e | Sorcerer/Wizard 5; Hit Dice-based lethal poison or Constitution damage |
| D&D 3.5e | Sorcerer/Wizard 5; same legacy Hit Dice thresholds and drifting vapour |
| Tactical effect | A 20-foot-radius poisonous cloud that blocks sight and moves 10 feet per round |
The Slow Poison
Cloudkill is dangerous because the threat does not stay where the caster puts it. In the older rules it rolls downhill, sinking into trenches, tunnels and cellars; the newest version instead specifies a moving magical Sphere without the old heavier-than-air rule. The poison can be a weapon against an advancing company or a disaster for people sheltering underground.
The edition determines whether the danger is poison damage or deadly Hit Dice thresholds and Constitution damage. The versions are not interchangeable, and holding one’s breath is not a universal answer.
Rules by Edition
Cloudkill — D&D 2024
Level/School: Level 5 Conjuration (Sorcerer, Wizard)
Casting Time: Action
Range: 120 feet
Components: V, S
Duration: Concentration, up to 10 minutes
Area: 20-foot-radius Sphere; Heavily Obscured
Saving Throw: Constitution for half
Damage: 5d8 Poison
When the fog appears, every creature within the Sphere makes a Constitution save against 5d8 Poison damage, half on success. Save again when the Sphere moves into the creature’s space, the creature enters it or ends its turn there. A creature saves only once per turn. The Sphere advances 10 feet away from the caster at the start of each of the caster’s turns.
A strong wind, including one created by Gust of Wind, disperses the fog and ends the spell. A slot above Level 5 increases damage by 1d8 per slot level.
Example: A pair of sentries in the Sphere must save immediately when the fog appears. On a later turn, moving into the cloud or remaining within it can force another save, but never two saves on the same turn. Unlike the old rules, no six-Hit-Dice instant-death threshold applies.
Cloudkill — D&D 2014
Level/School: 5th-level Conjuration (Sorcerer, Wizard)
Casting Time: 1 action
Range: 120 feet
Components: V, S
Duration: Concentration, up to 10 minutes
Area: 20-foot-radius sphere; heavily obscured
Saving Throw: Constitution for half
Damage: 5d8 poison
The poisonous mist spreads around corners. A creature makes a Constitution saving throw when it enters the area for the first time on a turn or starts its turn there, taking 5d8 poison damage on a failed save or half as much on success. Holding its breath or not needing to breathe does not avoid the damage.
The fog moves 10 feet away from the caster at the start of each caster turn and rolls along the ground, pouring down openings and seeking lower levels. Strong wind disperses it. The spell deals +1d8 poison damage for each spell-slot level above fifth.
Example: A scout already in the mist at the start of their turn must save. The 2014 text does not say that every creature already inside saves immediately when the spell is cast; that is a 2024 trigger.
Cloudkill — Pathfinder 1e
School: Conjuration (Creation)
Level: Sorcerer/Wizard 5
Casting Time: 1 standard action
Components: V, S
Range: Medium (100 ft. + 10 ft./caster level)
Effect: 20-foot-radius cloud, 20 feet high
Duration: 1 minute/caster level
Saving Throw: Fortitude partial; see text
Spell Resistance: No
Poisonous yellow-green vapour obscures sight as Fog Cloud and affects living creatures according to Hit Dice:
- 3 or fewer HD: die automatically, with no saving throw.
- 4–6 HD: die unless a Fortitude save succeeds; a survivor takes 1d4 Constitution damage on the caster’s turn in each subsequent round within the cloud.
- Higher-HD creatures: take 1d4 Constitution damage on the caster’s turn in each round within the cloud, halved by a successful Fortitude save.
Six-HD source overlap: The published spell text also says “6 or more HD” for the last category, overlapping its “4 to 6 HD” instant-death category at exactly 6 HD. Resolve that printed ambiguity consistently with your GM before play rather than silently rewriting the rule.
Poison-immune creatures are unaffected; holding one’s breath does not help. The mist rolls 10 feet away from its caster per round, settles into low ground and openings, cannot penetrate liquids and cannot be cast underwater.
Example: A 3-HD guard caught in the cloud dies without a save; a 5-HD guard makes a Fortitude save to avoid death, but a successful save still leaves Constitution damage while the guard remains in the cloud.
Cloudkill — D&D 3.5e
School: Conjuration (Creation)
Level: Sorcerer/Wizard 5
Casting Time: 1 standard action
Components: V, S
Range: Medium (100 ft. + 10 ft./level)
Effect: 20-foot-radius cloud, 20 feet high
Duration: 1 minute/level
Saving Throw: Fortitude partial; see text
Spell Resistance: No
The moving poisonous fog blinds ordinary sight and deals damage according to Hit Dice. A living creature of 3 HD or fewer dies without a save. A creature of 4–6 HD dies without a successful Fortitude saving throw; even a survivor takes 1d4 Constitution damage on the caster’s turn each round it remains. More powerful creatures take 1d4 Constitution damage each round, halved by a Fortitude save.
Source note: The published SRD also describes the Constitution-damage category as applying to creatures of 6 or more HD, overlapping the previous 4–6-HD category at exactly six. Do not claim the original is unambiguous; settle its six-HD treatment at the table.
Holding one’s breath offers no protection. Poison immunity negates the spell. The cloud moves 10 feet directly away from the caster each round, rolling along the surface while sinking into low ground and openings. It does not pass through liquid and cannot be cast underwater.
Example: A 2-HD soldier caught in the rolling mist dies without a save. A 5-HD bodyguard must save to avoid immediate death; a successful save still leaves the creature taking repeated Constitution damage while inside.
What Is Happening Right Now?
At a city gate, a mage has released poisonous vapour into the roadway. The defenders have taken refuge in the cellars, unaware that the legacy form of the spell sinks through every crack into the lowest chambers. The party must lead civilians to higher ground, disperse the fog, or confront the caster before the next round.
Adventure Hooks
The Cellar Refugees
Fleeing families descend beneath a granary while poison vapour creeps through old drainage tunnels. The party has one chance to divert the retreat upward before the fog reaches them.
The Silent Watchtower
An outpost reports that its sentries vanished without a fight. A survivor remembers green mist rolling past the gate, but the caster might still be hiding among the rescue party.
Related Magic
Fog Cloud provides obscuring cover without poison. Incendiary Cloud uses fire rather than poison and has different damage and movement rules. The official D&D 2024 Cloudkill and D&D 2014 Cloudkill establish different saving-throw triggers.
Sources and Licensing
The Pathfinder 1e and D&D 3.5e legacy mechanics are Open Game Content under the Open Game License v1.0a. Sources: Pathfinder 1e Core Rulebook, D&D 3.5e SRD, D&D 2024 Basic Rules and D&D 2014 Basic Rules. The old site featured J. M. W. Turner’s Rain, Steam and Speed (1844), a public-domain painting. It is retained in the attribution history but not as a spell-specific hero. Encounter scenes and explanatory text here are original.
Keep this reference growing
If this page helped with your reading or game, you can support its upkeep or explore the curated books.
Explore the Bookshop — epics, classics and stories behind imagined worlds.