On overlapping swarms


Rules Questions


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Pathfinder Adventure Path, Lost Omens Subscriber; Starfinder Charter Superscriber

In our last game our GM attacked us with nearly a dozen identical swarms, having them overlap and inflict their damage nearly a dozen times. I informed her that I did not believe that was the way swarms worked, and that they should be contiguous, forming one large swarm that does damage only once at a time.

Was I right in this?

What happens if you have swarms of different types? Could they overlap then and deal multiple instances of damage then? Would they destroy each other?

Scarab Sages

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Swarms of different types should be damaging each other when overlapped.

Multiple instances of the same swarm should just form a larger mass with more hit points (or track damage separately for each segment).

The Exchange Owner - D20 Hobbies

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Swarms differ in Pathfinder from 3.5. In 3.5 all swarms were shapable; In pathfinder only swarms of multiple swarms.

They can also move across you and damage you, so she could have all 10 of them move across you and stop elsewhere. Each one of them dealing damage. But only the one on you will cause distraction.

As for more than one swarm in a square, it comes down to which rules you prioritize.

Core wrote:
25 Diminutive creatures or 100 Fine creatures can fit into a single square.
Bestiary wrote:

Tiny creatures consists of 300 nonflying creatures or 1,000 flying creatures. A swarm of Diminutive creatures consists of 1,500 nonflying creatures or 5,000 flying creatures. A swarm of Fine creatures consists of 10,000 creatures.

Swarms of nonflying creatures include many more creatures than could normally fit in a 10-foot square based on their normal space

Either you work with the limits on diminutive and fine creatures that fit in a square (non-flying) or you ignore those limits by prioritizing the "many more creatures than could normally fit" rule.

Both interpretations are RAW.

Sovereign Court

@Ravingdork: it looks to me like your GM did it wrong.

Let's start by selecting a scenario. Either you're facing one really big swarm, or you're facing several swarms.

If it's one big swarm, it can only attack you once per turn, because:

Bestiary, Swarm subtype wrote:
Swarm Attack: Creatures with the swarm subtype don't make standard melee attacks. Instead, they deal automatic damage to any creature whose space they occupy at the end of their move, with no attack roll needed. Swarm attacks are not subject to a miss chance for concealment or cover. A swarm's statistics block has “swarm” in the Melee entry, with no attack bonus given. The amount of damage a swarm deals is based on its Hit Dice, as shown below.

So a swarm will only damage you if it ends its move in your square, and only once per round. The damage it does is not strictly related to the amount of 10ft squares it occupies, only its HD. Although swarms with lots of HD might actually cover more 10ft squares.

So if your GM was using one single swarm, he should've damaged you only once per round. It doesn't really matter that the swarm is shapeable; it only deals damage once, it doesn't matter how many of its component squares are folded into your square.

---

The alternative scenario: you're facing multiple swarms that choose to all land on you. This doesn't work either;

same entry, different emphasis wrote:
Swarm Attack: Creatures with the swarm subtype don't make standard melee attacks. Instead, they deal automatic damage to any creature whose space they occupy at the end of their move, with no attack roll needed. Swarm attacks are not subject to a miss chance for concealment or cover. A swarm's statistics block has “swarm” in the Melee entry, with no attack bonus given. The amount of damage a swarm deals is based on its Hit Dice, as shown below.

If multiple separate swarms end in the same squares, they'll also eat each other.


Ascalaphus wrote:


If multiple separate swarms end in the same squares, they'll also eat each other.

But temporarily will deal it to you too, maybe (till they kill each other)?


Do swarms have immunity to other swarms? Does swarm damage count as a 'weapon'?

This came up last week, and we couldn't find rules for it.

Scarab Sages

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I would say swarms are an area effect damage, and are thus vurnerable to other swarms.


I think I'd increase its size category and damage die... But I have no idea what the official rule is. (Also swarms no longer being shapeable is b$!*+*++! Why did they add that rule? It makes no sense!)

Grand Lodge

More of a clarification. Swarms are ugly, to begin with. Fully shapeable swarms should have a higher CR, as they are significantly more dangerous.

From the rules:

Swarm Subtype wrote:

A single swarm occupies a square (if it is made up of nonflying creatures) or a cube (of flying creatures) 10 feet on a side, but its reach is 0 feet, like its component creatures.

Larger swarms are represented by multiples of single swarms. The area occupied by a large swarm is completely shapeable, though the swarm usually remains in contiguous squares.

And, to be honest, now that I look again, that "completely shapeable" should probably be qualified as being completely shapeable as 10' squares or cubes, rather than leaving that part out.


Pathfinder Adventure Path, Lost Omens Subscriber; Starfinder Charter Superscriber

What about the following rules passage? Does it not support my statement?

Larger swarms are represented by multiples of single swarms. The area occupied by a large swarm is completely shapeable, though the swarm usually remains in contiguous squares.

Grand Lodge

The problem is there's a difference between "Larger swarms are represented by multiples of single swarms" and "Multiples of single swarms are always considered a single larger swarm."

I'm pretty sure any overlapping swarms would eat each other in addition to anything they're on top of, though.


Last fight I overlaped to spider swarm over a PC, I was not that the way to do it though.

An oficcial answer would be nice.


I've had swarms of different kinds attack each other, as when a party summoned a swarm of one kind to counter a swarm of another kind that was attacking them. But if 3 rat swarms pour into a room, I wouldn't let them damage each other, and for that matter I wouldn't let allied swarms overlap either; they take up space just like players fill 5' spaces. If there was only room in a chamber for one swarm, other allied swarms would need to bustle about in the hallway waiting their turn to get in, just like PC's trying to crowd into a small space. The only time I'd let swarms overlap is if they're opposed, in which case I'd deal with it conceptually like grappling.
But this is just what I think is reasonable; I'm not confident it's what the rules say.

Sovereign Court

I do think "completely shapeable" means that you can shape it in 10ft blocks. So if you had a larger swarm made up of 4 swarms, you'd be able to form all the Tetris shapes.

It's somewhat possible to cram them together tighter, but that's basically compressing a creature. The swarm is treated as a single entity, after all. I imagine it as basically over-filling the available space. If you try to pile more than 5000 bats in a 10x10x10ft area, some will just spill out of the area. Just the rules quietly assume you can't squeeze if you're not in a restricted space.

It's still not going to do more damage, because the whole uber-swarm is treated as a single creature, having a single turn, and dealing damage at the end of its move.

Liberty's Edge

Pathfinder Companion Subscriber; Pathfinder Roleplaying Game Superscriber
James Risner wrote:

Swarms differ in Pathfinder from 3.5. In 3.5 all swarms were shapable; In pathfinder only swarms of multiple swarms.

They can also move across you and damage you, so she could have all 10 of them move across you and stop elsewhere. Each one of them dealing damage. But only the one on you will cause distraction.

As for more than one swarm in a square, it comes down to which rules you prioritize.

Core wrote:
25 Diminutive creatures or 100 Fine creatures can fit into a single square.
Bestiary wrote:

Tiny creatures consists of 300 nonflying creatures or 1,000 flying creatures. A swarm of Diminutive creatures consists of 1,500 nonflying creatures or 5,000 flying creatures. A swarm of Fine creatures consists of 10,000 creatures.

Swarms of nonflying creatures include many more creatures than could normally fit in a 10-foot square based on their normal space

Either you work with the limits on diminutive and fine creatures that fit in a square (non-flying) or you ignore those limits by prioritizing the "many more creatures than could normally fit" rule.

Both interpretations are RAW.

Sorry Risner, but the bolded part is wrong. A swarm damage you only at the end of its move.

PRD wrote:


Swarm Attack: Creatures with the swarm subtype don't make standard melee attacks. Instead, they deal automatic damage to any creature whose space they occupy at the end of their move, with no attack roll needed. Swarm attacks are not subject to a miss chance for concealment or cover.

Note that is move, not move action. So the swarm make all of its move, single or double action is irrelevant, and then damage what is in the space it occupies.

- * -

I agree with you RD, several swarms made of the same kind of creatures will form a larger swarm, not share each other space.

Swarms made of different creatures can occupy the same space, but they will attack and damage each other, not only the non swarm creatures.

The rules are sufficiently vague that a GM can interpret them differently, but that don't seem to be RAI and it require some stretching to the interpreted as RAW.

Sovereign Court

Basically, if you as a GM want an uber-swarm, make a swarm with higher HD, then you get more damage.

It's entirely plausible that such an increased-HD swarm would also be bigger, occupying more squares. The Monster Advancement rules state that as a general guideline, a monster whose HD increases by 50% or more should increase in size. However, in the case of swarms, such an increase in size is somewhat more aesthetic, because you wouldn't be increasing the size of component critters. You're just covering a larger part of the battlefield; attacking more creatures but also more exposed to AoE effects.

For example, I might make a Double Whopper Rat Swarm, creating a 6HD (instead of 3HD) rat swarm that also occupies 2x10x10ft, because it's two rat swarms glued together. It would do 2d6 damage in each of its 8 squares.

The Exchange Owner - D20 Hobbies

Diego Rossi wrote:
Sorry Risner, but the bolded part is wrong. A swarm damage you only at the end of its move.

Thanks, you are indeed right.

I wonder if this is another change from 3.5.

Grand Lodge

Pathfinder Adventure Path, Starfinder Roleplaying Game, Starfinder Society Subscriber

Depends on the swarms involved. There's no reason a swarm of flying creatures can't exist in the same square as a swarm of creepy crawlies.

Shadow Lodge

Swarm subtype wrote:
The area occupied by a large swarm is completely shapeable, though the swarm usually remains in contiguous squares.

The way I'm reading the rule on being shapeable says to me that while a 10x10 "large" swarm should usually be a square, if it needs to go down a 5ft passageway, it can reshape itself down that passageway to get through it, without squeezing, and once it clears that passageway, it shapes itself back into a 10x10 swarm to the best of its ability as soon as it's feasible to do so.

In other words, it won't shape itself to a tetris-style S block willy-nilly in the middle of a 30x30 foot room - it'll be a square.

Grand Lodge

Swarm size and shape

Been there, done that. Jiggy has some good points in that thread.

Sovereign Court

Avatar-1 wrote:
Swarm subtype wrote:
The area occupied by a large swarm is completely shapeable, though the swarm usually remains in contiguous squares.

The way I'm reading the rule on being shapeable says to me that while a 10x10 "large" swarm should usually be a square, if it needs to go down a 5ft passageway, it can reshape itself down that passageway to get through it, without squeezing, and once it clears that passageway, it shapes itself back into a 10x10 swarm to the best of its ability as soon as it's feasible to do so.

In other words, it won't shape itself to a tetris-style S block willy-nilly in the middle of a 30x30 foot room - it'll be a square.

The thing is, a standard 10x10ft swarm is not a "larger swarm"; it's a normal basic swarm. It's just that the area occupied happens to be the same footprint as that of a Large creature.

A "larger swarm" would be a cloud of 20.000 wasps that assembles in 4 10x10ft squares, and it prefers those 4 squares to remain contiguous.


Bit of an old thread, but if swarms can't overlap, what is the point of Army Ant Swarm's ability Consume? Except for Large or larger creatures, no swarm would be able to nauseate and then use the Consume ability on anyone, because the targets would lose nauseated before the ants could take another turn. I suppose they could become nauseated from some other source, but how often is that the case?
Since Consume requires nauseated (or helpless, to be fair) and distraction causes nauseated, it seems it was designed for having multiple swarms on one target? Or maybe it's just really poor design, and they forgot nauseated from distraction only lasts one turn?

Any ideas?


I'm not sure. Since its Organisation line suggests they can roam around in multiple swarms, it might've been intended for them to stack on top of each other. First swarm nauseates, second swarm consumes. But IMHO that's such a dick move, I wouldn't allow it. That's 9d6 in one turn from 2 CR5 creatures.
Another interpretation is that there might be something else that's capable of nauseating. Maybe it's in a swampy environment, a spell effect that nauseates such as Stinking Cloud, and so on.
Another interpretation is that the ants clinging to the PC might've been able to nauseate as well. That's a nice two-part combo. But either they forgot to put that in, or was removed during an edit and now it's lost its synergy.
My bet is on bad design. There are more spells and creatures that interact poorly with themselves. And swarms are annoying enough as it is, I see no reason to buff them even more.


Fair points. There are A LOT of rules and creatures and spells, and probably a lot of different people creating the content, so I suppose there's bound to be some stuff that don't work quite as intended.

My players are about to run into some Army Ant Swarms in the next session, and wanted to get as good a grasp one those things as I could. The Cling ability is kinda cool though, so they're not a complete waste :)


forger42 wrote:
Bit of an old thread, but if swarms can't overlap, what is the point of Army Ant Swarm's ability Consume?

I think it's intended that they need something else to make their target nauseated/helpless.

In real life army ants are incredibly dangerous if you can't move out of the way, but if you can then you just out-walk them.

The idea seems to be that you have to help any infants/elderly/stunned-teammates so they don't get eaten.


I guess that's a possible interpretation. Just not very exciting against an OP adventuring party :P


Looking at the wording for army ant swarm, and the universal monster rules for swarms and distraction ability, it could be ruled that a character leaving the army ant swarm becomes nauseated at the end of their turn (when they take the 3d6 cling damage). Since the distraction ability says nothing about having to be swarm damage, only taking damage from a creature with the distraction ability, it would seem possible/reasonable to apply it in that instance.

If you opt to view it this way, that means at the end of their turn after moving away, a creature takes the cling damage and (if they fail their save) becomes nauseated for 1 round (until the start of their next turn), potentially allowing the remaining swarm (which took 1d6 damage from the cling ability) to then move over them on its turn and deal its 6d6 swarm damage from the consume ability.

In regards to the original thread topic, I probably wouldn't stack swarm damage from overlapping swarms of similar creatures (without good reason), but I have no problem with them overlapping or taking each other spaces. Swarms have always been able to share spaces with other creatures and can move through spaces far smaller than the area they take up (ie. despite filling a 10 foot cube, a bee swarm can come under a door or through a crack if its big enough for the constituent creatures to do so). So unless you're trying to say there isn't room for a bee to fly around in the space of a bee swarm, it's doable (but again, I wouldn't double the damage).

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