"Hold,” the rogue said. The entire party stopped behind him in the middle of the spiral staircase.
“What’s the holdup?” the fighter asked. A less-than-subtle note of irritation colored her voice. “You’re not telling us that the necromancer trapped her own tower staircase? The one that she uses daily?”
The rogue shot her a nasty glare and held out a finger to silence her. He turned his gaze back up the stairwell. His flat nose twitched and his black eyes began to water. “Do you smell that?” he asked.
“Now that you mention it, I do,” the wizard said. He shuffled his small gnomish body past the fighter and emerged next to the rogue. “An alchemical smell, perhaps? Some form of chemical compound, a bleaching agent, perhaps? Lye… or some derivative, I suspect.”
The rogue’s eyes widened, and he took an involuntary step backward. “Everyone off the staircase,” he muttered. He whirled around to look at his party, panic scrawled across his face. “Everyone back! Now!”
The heavily armored dwarf cleric in the back rank began fumbling to turn about in the cramped stairwell, and the fighter nimbly leapt over him, taking the stairs three at a time. The rogue stooped and grabbed the gnome wizard by his hood and slung him onto his shoulder. The wizard looked back up the staircase as the party fled, and felt a tingle of magic along his white whiskers. A second later, he saw it: the cloud of thick, yellow-green gas billowing rapidly down the staircase behind him.
“Oh! Oh my!” the wizard gasped. The gas surged into his face and he felt a terrible stinging as he screwed his eyes shut. His mustache shriveled and disintegrated as the caustic gas ate away at its bristles. He threw his cloak around his face and turned to face forward. “Run, everyone!” he coughed. “It’s a cloudkill! Cloudkill!”
I really used cloudkill like a dummy last week. My suboptimal use of cloudkill was sort of purposeful—it was in a fight I wanted the characters to win—but it was also due to my own half-remembered understanding of the spell rules. Once I flipped away from my monster’s stat block and actually read the spell as written in the Player’s Handbook, I felt a little twinge of regret for so royally mucking up my lich’s strategy.
I didn’t worry about it too much, because it was still an exciting fight on the whole, but I still feel like I could have made it even better if I fully understood how cloudkill worked before I committed to using it.
What Does Cloudkill Do?
As a 5th-level spell, cloudkill had better be packing some serious punch. It comes with four main effects:
- Initial area-of-effect damage. While cloudkill doesn’t deal damage instantaneously upon casting, like a fireball, it does require all creatures within its 20-foot-radius area to make a Constitution save at the start of each of their turns, taking 5d8 poison damage on a failed save or half as much on a successful one. This almost guarantees that every creature in the spell’s area will take damage.
- Obscuration. This is an easy rule to overlook, but the cloud’s entire area is heavily obscured. All creatures within the cloud are blinded. As usual, creatures with blindsight suffer no vision penalties while blinded.
- Ongoing effects. The cloud lingers on the battlefield, continuing to deal damage and obscure vision, as long as its caster maintains concentration.
- Movement. The caster can’t move the cloud directly, but it does move on its own. At the start of each of the caster’s turns, the cloud moves 10 feet away from the caster, “rolling along the surface of the ground.” The cloud is heavier than air, so it sinks to the ground and even passes through holes or grates in the ground.
So, how does cloudkill measure up? Its initial damage isn’t anything to write home about. A mere 5d8 poison damage is less than a fireball. (The average of 5d8 is 23, the average of 8d6 is 28.) So, in order for cloudkill to out-damage a spell two levels lower than it, it needs to deal damage on at least two turns.
This isn’t easy on most battlefields. The cloud’s radius is only 20 feet, so a creature with 30 feet of movement always has at least one way of escaping the cloud’s area. This problem is only exacerbated by the fact that the cloud automatically moves 10 feet away from the caster on their turn, making it challenging to keep the cloud centered on your enemies, especially if they are charging right at you. All this is to say nothing of the many creatures who resist or ignore damage; most (if not all) undead and fiends (and a smattering of other creatures) are completely immune to poison damage. It also has the troubling weakness of being able to be dispersed by strong wind, such as those created by the 2nd-level spell gust of wind.
All this to say, while cloudkill may look like another area-of-effect damage spell, its actual applications are much subtler. I made the mistake of using it like a fireball in my home game last week, and while it did a nice chunk of damage to the entire party, it was relatively unimportant in the grand scheme of things. If I had planned a bit better, cloudkill could have devastated the party. Why?
Cloudkill is a Combo Spell
While cloudkill is relatively underwhelming on its own, it is not without its uses. Just like constructing a combo in card games like Magic: the Gathering or Hearthstone, individual spells that may seem underpowered can create a truly nightmarish scenario when played in tandem. Here are some combos that turn cloudkill from a C-list spell into a grade-A monster-killer. (Or player character-killer, depending on which side of the DM screen you prefer to play from!)
Comboing Cloudkill as a Player
Since cloudkill requires your concentration, creating combinations with your own spells can be difficult. However, if you’re playing a sorcerer or wizard (or bard who has learned cloudkill through their Magical Secrets feature), you should try teaming up with another spellcaster in your party to discover wicked spell combinations.
Cloudkill works best when you have an environmental advantage. This could mean that you have the high ground and the enemies have to climb to reach you (such as up a cliff or staircase), or it could mean that your enemies are caught in a space with little room to maneuver, such as a box canyon or a dungeon corridor. Since an area’s environment is typically dictated by the Dungeon Master, you’ll need to find other options. This could involve you manipulating the environment with magic, finding ways to hold your enemies in place, or controlling their movements. Here are some strategies and sample combos:
- Encaging. By trapping your foes within a magical cage, you can both keep yourself safe from their attacks and trap them inside your cloudkill’s radius. Wall of force is the gold standard as far as this combo is concerned, though wall of stone is a useful alternative with a larger area of effect. Since this spell requires concentration, you’ll unfortunately need two spellcasters of 9th level or higher to pull this combo off. Forcecage provides an even more reliable version of this combo and doesn’t require concentration, though it does consume a valuable 7th-level spell slot.
- Immobilizing. By preventing your foes from moving, you can trap them in the cloud—until it rolls away from them, anyway. A grappled creature can’t move, so a strong character willing to take some poison damage (or who is resistant to poison, like a dwarf, or immunized to poison damage, such as through a druid’s Elemental Wild Shape) can wade into the cloud and hold them down. Restrained creatures, such as through the ensnaring strike spell are also immobilized, and creatures that are paralyzed by spells like hold person are also at the mercy of the cloudkill. Try having a fellow spellcaster cast hold person at a higher level to paralyze even more of your enemies!
- Forced Movement. Since cloudkill deals damage when a creature starts its turn in the cloud and the first time on a turn that it enters the cloud’s radius, your allies can use abilities that force enemies to move to hurl them into the cloud. Such effects include command, fear, thunderous smite, thunderwave, the warlock’s Repelling Blast or Grasp of Hadar (Xanathar’s Guide to Everything) invocations, or even the good old-fashioned Shove action. A well-coordinated party could play ping-pong with an enemy, pushing them into the cloud, dragging them out, and pushing them back in again for massive damage every turn… though your DM probably won’t be too happy seeing their fearsome baddie turned into a glorified shuttlecock.
Comboing Cloudkill as a Dungeon Master
Dungeon Masters have a lot more ways to realize cloudkill’s true destructive potential than their players do, since they have the power to design encounter environments and have the benefit of gearing the monsters’ abilities towards a specific encounter. They also have the major advantage of being able to stack the deck by filling encounters with dozens of minions to keep their cloudkill-casting masters safe from harm. While Dungeon Masters using cloudkill should try to immobilize enemies, move them about, and trap them just like players do, they have many different options at their disposal. Here are just a few ways you can do this as a Dungeon Master, and even a few DM-specific options:
- Creating Advantageous Battlefields. As the DM, you can design the terrain of your encounter area. While terrain isn’t factored into the math of the Challenge Rating system, giving your enemies advantageous terrain can seriously impact the difficulty of an encounter. Since cloudkill drifts downward, a spellcaster at the top of a 30-foot-high (or higher) cliff can cast the spell, causing it to drift down and deal damage over multiple turns as the characters attempt to scale the cliff. Or, perhaps the fight takes place in a natural crater; the villain hides high above the crater, but projects a major image of their form in the pit. Then, when the characters enter the deep crater, the villain cackles, dispels the illusion, and casts cloudkill within the high-walled pit.
- Spellcasting Allies. Cloudkill’s troublesome concentration requirement is less troublesome to DMs than it is to players. Just add a mage to your combat encounter, deck them out with mage armor and a shield spell, and have them prepare spells to either encage the characters like wall of force or wall of stone, or to immobilize them like hold person. Heck, do both! This extra spellcaster’s entire job is to stop the party after their master casts cloudkill and then hide so that their concentration can’t be disrupted by any allies that escape the deathtrap. Adjust your perception of the encounter difficulty accordingly, of course. This mage won’t be hurling fireballs (probably), but being able to spring this kind of ruthless trap on your characters is even more deadly than a fireball or two.
- Undead Allies. Cloudkill is a potent spell in the hands of a villainous necromancer, a spellcasting vampire (see the variant vampire options in the Monster Manual!), or a lich because these powerful spellcasters tend to bring their undead minions as backup. Since the undead are immune to cloudkill’s poison damage, they can wade into the cloud and attack the players with impunity. Imagine a cloudkill surrounding the players, a wall of stone rising up around them, and then a horde of shrieking vampire spawn scaling the wall! Similarly, a warlock of the Fiend could bring along some poison-immune demons or devils to do the same, and a transmuter could bring along a golem or other constructs.
Create your own Combos
These clever uses of cloudkill are only the tip of the iceberg when it comes to this spell. What are some other ways you can use this spell to wreak havoc upon your players’ characters—or your DM’s monsters? There are certainly ways unique to your own party—perhaps instead of a wall of stone, your party wizard knows Evard’s black tentacles and can use that to restrain your targets while you enwreathe them in noxious fumes. Planning combination moves with your party members is one of the best parts of D&D, and one I rarely see utilized. Party-wide plans of attack happen all the time, but intra-party combos? That’s something that will really make you stand out from the crowd.
James Haeck is the lead writer for D&D Beyond, the co-author of Waterdeep: Dragon Heist and the Critical Role Tal'Dorei Campaign Setting, and is also a freelance writer for Wizards of the Coast, the D&D Adventurers League, and Kobold Press. He lives in Seattle, Washington with his partner Hannah and his two stinky kitties, Mei and Marzipan. You can usually find him wasting time on Twitter at @jamesjhaeck.
Excellent article, and gets some ideas going!
Small point/question regarding command: the spell says it has no effect if the command is "directly harmful to it." I've been interpreting this as not being able to command someone to jump off a cliff that they know is high enough to hurt/kill them. Wouldn't this also apply to not being able to command them to walk into a cloudkill? Have I been using command wrong?
The only thing I don't like about cloudkill is its name. Using it in a sentence is so awkward. Couldn't they have named it killing cloud or death fog?
A lot of these combos could apply to Sickening Radiance as well. That's another spell that can be hard to get the most out of (unless the environment is providing a bottle-neck.)
Casting spiked growth between the cloud and the exit would also seem rather cruel. Especially if the party’s was in the cloud and unable to see it cast. Making an illusionary exit down a blind alley and casting the cloud kill so that it drifts in that direction also be a nasty tactic if the Lich had a free turn to prepare before the party entered the area.
haha, being a DM is lots of fun until someone dies.
I love this spell it was sooooooo useful in The Rise Of Taimat campaign.
Great I was looking for things that I could include in a Tomb of Horrors / Tomb of the Nine Gods type of trap dungeon.
Not so useful if anyone has levitate - they would be able to hover over it.
Some reasons why Melf's Acid Arrow is great.
It's a ranged spell attack, meaning like other spell attacks you get the chance to roll a natural 20 and critical hit for 8d4 acid damage + 2d4 acid damage at the end of the target's next turn (10d4, that's 10 turns worth of dagger stabs you didn't have to do XD who has time for that).
Also being a spell attack, anything that offers advantage to attacks gives you advantage on this spell attack and anything that messes with the enemy AC helps you also.
It's actually fairly helpful against messing with enemy casters. 2 separate instances of damage, means 2 different concentration rolls. That gives you 2 chances to interrupt an enemy casters concentration spells and 2 separate chances you give them to roll nat 1's.
It's acid damage, meaning it can often bypass different damage resistance or immunity, also it can come into play with certain specific monsters. Trolls for example are notorious for not dying. This spell denies them their powerful regeneration for up to 2 turns.
Even if you fail you still do 2d4 damage, that's sometimes better than other failed, for example scorching ray can wiff and deal no damage at all if you roll too low.
There is a potential mage combo with Elemental bane. While this isn't connected to Melf's directly it's still a way to deal potentially a free 4d6 additional acid damage on top of the damage of the arrow itself.
Reasons why it's bad, at worst you're looking at 2d4 damage for a level 2 spell slot, which is let's face it god awful even when compared to cantrips.
It's only 1 spell attack, meaning you can easily get shafted with 1 and do only 2d4, Searing ray has 3 attacks and can be much more forgiving and does higher damage.
Elemental damage weakness. Acid like all elemental damage, is prone to the fact that something somewhere will be resistant or immune to it's damage. It's not a great idea to overly depend on 1 type of elemental spell damage.
Even for a level 2 spell the damage is on the low end, dealing 6d4 total on a success or 2d4 on a failure.
This is a single target spell, crits can easily waste damage. Again compared to scorching ray with 3 crits, 12d6 damage to 1 creature, 4d6 and 8d6 to 2 different creatures or 4d6 to 3 different creatures, compared with 8d4 + 2d4 next round to only 1 creature.
All things considered I'd say Melf's Acid Arrow is not a bad spell by any means. This is a great opener spell against enemies you know little about, it's more of a fact finding spell, you can prod with it and deal some damage, testing the defenses of an enemy. If you roll a 19 against some armor clad knight, but still miss and only do 2d4 damage then you know this a high AC target and might want to use your save based spells instead of burning spell attacks which could easily miss and make you sad. Perhaps make your next spell a Intelligence, Charisma or Wisdom save spell designed to confound or manipulate your target, opening them up for later abuse further into combat. I'd personally suggest something like hold person in this scenario, and gift your melee friends a free complementary critical hit against your currently paralyzed foe.
I'd argue that when a caster decides to make a Cloudkill all creatures within the area don't take any damage until the start of their next turn, only because of Incendiary Cloud. The level 8 spell states "When the cloud appears, each creature in it must make a Dexterity saving throw." vs damage. Cloudkill doesn't say that. However I'd also say that the instant the spell is cast, the effect of heavily obscured should be applied to all creatures within the area.
Interesting comparison but, Incendiary does damage when a creature ends a turn within the cloud or enters the cloud for the first time on a turn, so it needs to have that initial burst of damage, otherwise people could just leave during their turn and take 0 damage from a level 8 spell. XD wow that'd be useless.
Nice I liked reading that
cloudkill + black tentacles = death you need two casters but still death
can you please do a spell spot light on evard's black tenteclas?
Hunger of hadar and cloud kill would hurt.
That's a very brutal combo not for the faint-hearted. At least for a DM to use - that's probably a tier 3 or 4 encounter move! ...thanks for the idea. ;)
Glyph of warding at high level spell warding version no concentration required. Caveat have to stay within 10 feet of were you cast it until it goes off. once triggered full duration. SO MANY POSSIBILITIES.
Once the DM has used Cloudkill against the party, he could later use Minor Illusion to recreate the appearance of it and freak the players out for a minimal cost.
A couple folks already mentioned Grease, but here's a wild idea, Tiny Servant.
A tiny servant is immune to poison damage and has blindsight for 60 feet. It (or a few of them) can run through the cloud hacking at the heels of your enemies without being seen and thus not triggering opportunity attacks. Further if you animate something like caltrops (bag of 20) you can command them to ready an action to spread those caltrops directly in front of an enemy trying to escape. The caltrops could stop a foe in their tracks that turn and reduce their speed by 10 feet making it that much harder to escape the cloud next round.
It's an hour to cast tiny servant but the servant will last for 8 hours so it can be around for the better part of an adventuring day allowing you ample time to prepare.
To what extent can a Dust Devil spell disperse, move, or otherwise counter a Cloudkill? Been scouring the internet and can't find anything on this, surprisingly.
RAW? To no extent.
Cloudkill is dispersed by "strong wind" and Dust Devil doesn't have any mention of creating a strong wind despite being able to move creatures and kick up dust. Further, cloudkill's movement isn't defined as based on the direction of the wind it just moves away from the caster. Spells tend to specifically mention when they create a strong wind such as Gust of Wind and Warding Wind. So those spells can absolutely disperse cloudkill but Dust Devil cannot.
That all said the DM can make their own ruling on the matter if they feel it ought to be otherwise.