D&D 5E Ruling Question: Swarms and Repelling Blast

[ezo]

In our game tonight a Warlock PC hit a swarm of rats with his eldritch blast. The Warlock has the Repelling Blast eldritch innocation.

What would be your ruling: does the repelling blast affect the swarm of rats, pushing the swarm up to 10 feet back in a straight line?

 

[Hexmage-EN]

I'd just flavor it as knocking back a large enough number of the swarm that those unaffected scamper over to the others.

 

[DrJawaPhD]

I can't find anything in the rules that would prevent the knockback from occurring, so yeah I'd say a bunch get hit and knocked back with the rest scurrying alongside to stay together

That's silly and unrealistic but no more so than many other mechanics with swarms, like a single arrow shot killing all the rats if you roll enough damage.

 

[Clint_L]

I'd let it happen, but if it breaks immersion for you, then rule the other way.

 

[ezo]

Well, not many votes, but I'm in the minority so far LOL!.

As DM, I ruled no at the time and here is why:

Repelling blast affects a (singular) creature. A swarm is not a singular beast. Other SA rulings, involving things like Wild Shape of example, state a swarm is several creatures--hence why you cannot Wild Shape or Polymoprh into a Swarm of Rats.

Also, giving the conditions immunities: grappled, prone, restrained, the ability to "shove" (a form of a special attack akin to grapple and knock prone) or push the swarm as a creature narratively didn't make sense in the moment.

I'd just flavor it as knocking back a large enough number of the swarm that those unaffected scamper over to the others.

I'd say a bunch get hit and knocked back with the rest scurrying alongside to stay together

Something like this could work IMO.

I'll have to discuss this in our next session with the group to decide how we want to proceed in the future. I'm still inclined to rule no in the future, but we'll see.

FWIW, the swarm surprised our rogue, hit for 7 damage, and had initiative so hit again the second round for another 7 damage before the rogue has his turn. So, the rogue went from 17 hp to 3 hp. The repelling blast would have pushed the swarm back so the rogue could move back without provoking an OA. It was a non-issue, since the rogue used cunning action to disengage before retreating behind the tank.

 

[Oofta]

Any attack that affects the swarm in a significant way is hitting the majority of the individuals in the swarm. Swarms are a bit weird to damage altogether, it's why they have resistance to just about anything but AOEs. I just envision the blast incinerating multiple rats and then there being a bit of an explosion. Same way a sword swing is slicing through multiple rats or a shield bash just scoops up a large number and hurls them. For game purposes, a swarm is a creature.

If you have issues visualizing this, swarms may just not work for you.

 

[Warpiglet-7]

Well, not many votes, but I'm in the minority so far LOL!.

As DM, I ruled no at the time and here is why:

Repelling blast affects a (singular) creature. A swarm is not a singular beast. Other SA rulings, involving things like Wild Shape of example, state a swarm is several creatures--hence why you cannot Wild Shape or Polymoprh into a Swarm of Rats.

Also, giving the conditions immunities: grappled, prone, restrained, the ability to "shove" (a form of a special attack akin to grapple and knock prone) or push the swarm as a creature narratively didn't make sense in the moment.



Something like this could work IMO.

I'll have to discuss this in our next session with the group to decide how we want to proceed in the future. I'm still inclined to rule no in the future, but we'll see.

FWIW, the swarm surprised our rogue, hit for 7 damage, and had initiative so hit again the second round for another 7 damage before the rogue has his turn. So, the rogue went from 17 hp to 3 hp. The repelling blast would have pushed the swarm back so the rogue could move back without provoking an OA. It was a non-issue, since the rogue used cunning action to disengage before retreating behind the tank.

I said “other” initially but reread the rules.

If you cannot prone them and they share hit points as a group, I am thinking that any hit are obliterated. Additional hit points may simply represent more rats that were not hit. Would a rat have one or two hit points each? That is a ruling and not the rule…and I would be fine with that.

However:

Since it’s a monster entry, RAW I think they get pushed. Maybe when you cast the blast, you sweep the rays across several at once.

Whatever you do just be consistent and let players know the reasoning and precedent.

Perhaps if I said “no” but the caster is trying to save others I would have them make a roll to see cast it skillfully to “clean off” the effected character.

 

[Thommy H-H]

A swarm is a single creature in rules terms: anything that affects "a creature" also affects a swarm, otherwise most of the game wouldn't interact with them - not least the Eldritch Blast spell itself! The immunities, resistances, and other rules in each swarm's stat block already cover the exceptions that logically follow from their nature, and there are a few other instances in the rules where an exception is made for swarms. Specific beats general, but by the same token, general applies unless there is a specific rule that contradicts it.

In non-game terms, I don't really see why pushing an entire swarm back with an Eldritch Blast is a problem for immersion or verisimilitude! You can push lots of things at once? Like with a spade? I don't think Repelling Blast is (necessarily) working by some kind of mystic force on the psyche of a single creature or something; I read it as physically pushing the target away with the power of the blast of arcane energy. But the whole point of Eldritch Blast is it can be whatever you want it to be anyway.

 

[ezo]

For game purposes, a swarm is a creature.

If you have issues visualizing this, swarms may just not work for you.

But there are SA rulings that a swarm is not "a" creature, but several. It is why you cannot polymoprh a swarm of tiny beasts, it is not "a" beast.

I can visualize it just fine, but in the same respects a swarm cannot be grappled (and moved), shoved and knocked prone, or restrained. If you can push a swarm via eldritch blast, you should be able to push a swarm by shoving it.

One player last night thought of the beam hitting the swarm, and blasting enough that it pushed the majority back.

And of course, when a swarm reaches 0 hp, it doesn't necessarily mean every rat was killed, just that most were "defeated" and the swarm dispurses. That's my interpretation though.

Anyway, all in all I might lean the other way simply because it is an invocation, and warlocks don't get a ton of them, so not allowing it seems like an uncessary nerf, even if it turns out RAW or RAI it shouldn't work...

 

[ezo]

Would a rat have one or two hit points each?

They have 1 (average), but an individual rat could have as many as 3 hp.

Whatever you do just be consistent and let players know the reasoning and precedent.

Of course. Last night was a "ruling in the moment", but everyone understood I would consider it further and we would discuss it as a group later. It was one of those things done for expediancy during game time. Also, as I mentioned, it really was a non-issue in that particular situation.