Swarm damage & attack rolls

[J-H]

A swarm of spiders is supposed to be climbing all over their target, not just biting at the ankles. Why do they have to make an attack roll?

I'm planning to make a couple of higher level swarms (dread blossom & hellwasp from 3.5), but if they have a +4 or +5 to attack, they just aren't relevant against high level parties.

Is there precedent in the 5e ruleset for "If they're in your space, it's just a question of how badly you get hurt" enemies? The only one I can think of is the fire elemental.

[JackPhoenix]

For the same reason you have to make an attack roll to hit someone you're grappling with Shocking Grasp. The game is just written that way.

If the swarms have higher CR, they should have accordingly higher attack bonus.

[Mellack]

A swarm of spiders is supposed to be climbing all over their target, not just biting at the ankles. Why do they have to make an attack roll?

I'm planning to make a couple of higher level swarms (dread blossom & hellwasp from 3.5), but if they have a +4 or +5 to attack, they just aren't relevant against high level parties.

Is there precedent in the 5e ruleset for "If they're in your space, it's just a question of how badly you get hurt" enemies? The only one I can think of is the fire elemental.

If you want a verisimilitude reason, consider that spiders or most other tiny creatures cannot bite well through even thick clothing. A failure to make their to-hit roll can simply be explained as only a few were able to get to uncovered areas and didn't do enough to do hp damage. The defender was successful at brushing them away from the face, etc.

[J-H]

Hmm, true. I guess I can give them a really high dexterity - small bugs dodge fast and are really hard to block.

[Unoriginal]

A swarm of spiders is supposed to be climbing all over their target, not just biting at the ankles. Why do they have to make an attack roll?

A druid shapeshifted into a Tiny scorpion still has to do an attack roll even if they climb on a Huge Storm Giant.

It's not just hitting, it's also managing to actually affect the target. In the narrative space of the fight, for example, a DEX 6 Duergar King in plate armor with a magic shield likely has a lot of blows land on either protection, but said blows just fail to do anything because of the big armor.

Last time I DMed a swarm, I described it as the rot grubs failing to dig through the armor and clothes when they missed an attack.



I'm planning to make a couple of higher level swarms (dread blossom & hellwasp from 3.5), but if they have a +4 or +5 to attack, they just aren't relevant against high level parties.

You can give them higher attack mods. There's no problem with it.



Is there precedent in the 5e ruleset for "If they're in your space, it's just a question of how badly you get hurt" enemies? The only one I can think of is the fire elemental.

Several creatures damage on contact or everyone that stands too close (ex: the Remorazh) and there are some grappling effects or suffocation effects.


Hmm, true. I guess I can give them a really high dexterity - small bugs dodge fast and are really hard to block.

Or just give them higher attack proficiency.

[J-H]

I try to follow the rules with CR, meaning proficiency is tied to CR. It keeps things neat and clean.
If needed, I can add something like a trait:
Devourers of Flesh. Hellwasp swarms are proficient at burrowing past even the thickest chitin or armor plating. They have a +3 attack and damage bonus versus living creatures.

[NorthernPhoenix]

I try to follow the rules with CR, meaning proficiency is tied to CR. It keeps things neat and clean.
If needed, I can add something like a trait:
Devourers of Flesh. Hellwasp swarms are proficient at burrowing past even the thickest chitin or armor plating. They have a +3 attack and damage bonus versus living creatures.

I think copying the Fire Elemental (or certain oozes) is a perfectly valid option if you want to represent just being in the swarm causing constant, unavoidable damage.

[Unoriginal]

I try to follow the rules with CR, meaning proficiency is tied to CR.

Actually it's CR that's tied to proficiency.

As in, CR is based on the to-hit chance of the creature, its damage output, it's AC, it's HPs, and other factors which affect their damaging and survival potentials. It's not CR that decides what those things are (unless you're really aiming at a specific CR, I suppose).



Devourers of Flesh. Hellwasp swarms are proficient at burrowing past even the thickest chitin or armor plating. They have a +3 attack and damage bonus versus living creatures.

That's not really fitting the 5e design principles, but eh it won't destroy anything.

Speaking of 5e design principles, I can't believe I forgot 5e's ultimate "get damage as long as you're in its space" creature: the Gelatinous Cube.