Cloudkill has been kicking around the libram arcana for quite a while in Dungeons and Dragons. It’s also stayed relatively the same with each edition. So, what we have here is a dependable, stable, vicious little spell that everyone should consider having access to, one way or another. Even if you can’t cast it, you should consider homebrewing a magic item that can.
This spell has even made its way outside of Dungeons and Dragons. How many times has James Bond or Austin Powers been trapped in a room with steadily increasing poisonous gas? In the new battle arena shooter Apex Legends, the character named Caustic uses what is essentially cloudkill for his signature ability.
This post is all about this staple spell — who can cast it, who should cast it, and how to improve it. We even put a little surprise for the DMs at the end of this page. Check it out!
- Casting Time: 1 action
- Range: 20-foot sphere within 120 ft.
- Duration: 10 minutes
- Class: Sorcerer, Wizard, Death Domain, Circle of the Land (Underdark), Circle of Spores, Oath of Conquest, the Undead Alchemist
- Level: 5
- Damage/Effect: Poison
- Attack/Save: Constitution
- Components: Verbal, Somatic
- Ritual/Concentration: Concentration
Spell Description: You create a 20-foot-radius sphere of poisonous, yellow-green fog centered on a point you choose within range. The fog spreads around corners. It lasts for the duration or until strong wind disperses the fog, ending the spell. Its area is heavily obscured.
When a creature enters the spell’s area for the first time on a turn or starts its turn there, that creature must make a Constitution saving throw. The creature takes 5d8 poison damage on a failed save or half as much damage on a successful one. Creatures are affected even if they hold their breath or don’t need to breathe.
The fog moves 10 feet away from you at the start of each of your turns, rolling along the surface of the ground. The vapors, being heavier than air, sink to the lowest level of the land, even pouring down openings.
At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the damage increases by 1d8 for each slot level above 5th.
Who Can Cast Cloudkill?
This is a fairly common spell available to every spellcasting class excepting Ranger and Bard, provided they choose the correct subclass.
Who Should Cast Cloudkill?
Whether or not you take cloudkill depends on what your party’s role is. What type of spellcaster are you?
If you are a healing or support caster, you should probably not take cloudkill. If you are a dedicated damage-dealing spellcaster, you might consider taking steel wind strike or synaptic static instead. If, however, you are the type of spellcaster who likes to change the environment and force your foes into a battle over who has the most flexible thinking, cloudkill is definitely for you.
When Should You Cast Cloudkill?
The ideal situation in which to cast cloudkill is when you and your allies are walking down a corridor and your enemies are on the other end. If you put this cloud of caustic gas in front of you, you can essentially fumigate the entire dungeon while your allies pick off anyone who skitters away like so much vermin.
Also, cast this spell if your enemies happen to be underneath you in a ventilated room. The cloud will drain down the smallest of openings and fill their space. This aspect of the cloud can be used to help you find secret openings as well. Where does the cloud flow? Following it could lead you to a hidden passage.
Cloudkill pairs with the various wall and hold spells. While these spells all require concentration, if you have an allied spellcaster capable of maintaining such concentration, the pair of you can force your targets to remain in the cloud for the duration.
Alternatively, you could disguise the cloudkill spell inside of a casting of fog cloud. While the cloud flows around objects and corners, you can not split the cloud entirely. Because that would be super cool, we homebrewed a metamagic option to make it happen. Use this if you like:
Homebrew Metamagic Option: Split Spell
By spending two sorcery points, you may split any spell that has an area of effect into two separate areas of effect whose total square footage is equal to the original casting of the spell.
Thus, when casting cloudkill with this option, you can create two clouds with a 10-foot radius.
Metamagic abilities will vastly improve your cloudkill as well. Extended, heightened, quickened, and careful spell options are worth looking at if you have those available to you.
In addition, the poisoner feat does apply to the cloudkill spell. The feat’s description applies any time you roll poison damage, regardless of the source.
Cloudkill vs. Other Spells
Players often wonder if the gust cantrip will disperse a cloudkill. Let me solve that one for you right now: No. There. Argument solved. The gust cantrip can move objects, but it is not a fan. It is a targeted push of air against a single person or item.
If you want to disperse the cloudkill with magic, you must use the gust of wind spell at 2nd level. This is why cloudkill is allowed to be such a powerful spell at 5th level: it can be easily thwarted or avoided. Therein lies its game balance.
Common Questions About Cloudkill
In general, we usually get the same kinds of questions about this spell, so the HMFICs here at B. C. RPG whipped up a little FAQ for you VIPs so the PCs won’t be DOA. Got that?
How Does Cloudkill Move?
Cloudkill immediately emanates a 20-foot radius from a spot you choose. It does not grow. Instead, on your turn, the entire cloud moves 10 feet away from you in any direction (so long as that direction is not toward you). It does not split or change shape, though it does flow around obstacles and through enclosed spaces. This means you can push it along in front of you, but you can not pull it along behind you.
Can You Take Damage Twice?
You can take damage twice from cloudkill but no more than once per turn.
The spell says that “when a creature enters the cloud or starts its turn” it takes damage. If you cast the spell on a space a creature is occupying, then the creature has not entered the cloud. The cloud has just manifested. They will begin taking damage at the start of their next turn. If they remain in the cloud, say perhaps because of hold person, they will take damage again their next turn. If they do not start their turn in the cloudkill, but run into it, they take damage.
In short, a creature may only take damage from cloudkill on their turn.
Do You Take Damage if You Are Unconscious?
Yes, if you fail the CON save. While unconscious, you automatically fail Strength and Dexterity saves but not Constitution.
Can Cloudkill Move Past 120 Feet?
Yes. The spell states the cloud appears within 120 feet of you. After that first appearance, it can move 10 feet per round in any direction that is away from you, allowing you to steer it with your own movement for 10 minutes (concentration).
For the DMs
If you really want to use cloudkill in a frightening way, make it the basis of a trap down a long corridor. That being said, do not be afraid to hit your players with it. Quite a few races have resistance to magical effects and advantage on various saving throws. Use it as a way to winnow them down and make them a little nervous about what shows up on the other side of this cloud.
Since the cloud does poison damage, you should also consider filling the cloud with constructs that are immune to poison and have blindsight.
Use this dungeon feature sometime:
The Messed Up Hallway Our DM Put Us Through
In your next dungeon, create a 60-foot corridor. As soon as the players enter one end, cast a cloudkill on the other. It will move 10 feet per round down the hall. When that cloudkill moves 20 feet, send another one down the hall. Thus, you will have multiple cloudkills traveling down the corridor with a 10-foot gap between them. The gas obscures the corridor heavily, so they may not realize what is happening. This is good.
Line the corridor with as many animated armor monsters as you see fit. Make sure the corridor is only 10 or 15 feet wide. Your goal with the animated armor is not to defeat them but rather to slow them down. If you can block the path with the animated armor, the PCs will have to shove or teleport in order to avoid the cloudkill that is the real threat. See, the animated armor have Blindsight, which means the vision obscurement doesn’t affect them at all. If you like, you can substitute web traps as the 2nd-level spell in lieu of animated armor.
Finally, you could also put this corridor in a Yuan-ti-themed dungeon since the Yuan-ti have poison resistance. Although, given the obscured nature of the gas, the Yuan-ti might prefer to simply throw area-effect spells or alchemical items and hope to accidentally hit a PC.
Also, consider making the terrain especially muddy or overgrown so that it is considered difficult terrain. That will slow them down even more.