D&D 5E How to handle massive oncoming swarms

[Stalker0]

I know that this is a what swarm stat blocks are for, but swarms don't capture the continual streaming of monsters.

It can if we make a few tweaks.

1) Have the "swarm" be a huge size to start, and then subtract squares from its size as the party knocks down hp. This simulates them killing the dudes.

2) You can either use a swarm attack (auto damage), but if you want it to be a little more dynamic use the mob rules in the DMG. Just assume there are X amount of guys around a party member who is in or near the swarm (maybe 8 or a bit less if the party is doing well to keep the guys off of them). This way their AC still plays into it, and there is the feeling of being attacked.

3) As new dudes enter the room, add another swarm, or simply "heal" the existing swarm and then fill back in the squares.

4) Make sure to respect cleaving type abilities and area effects, you want to ensure the players feel they are getting the payoff for those abilities.


So that's a fine option. Another option is to go with ye old minions rules from 4e which are still one of the rules I wish 5e had kept. A refresher.

1) Minions have 1 HP. However, they have "evasion", they don't die if they pass a saving for half damage.
2) Minions have a weak attack with that deals a small amount of static damage.

The rules work great for hordes about hordes of guys in a way that makes the party feel like they are cutting through wave after wave of people.

 

[Shiroiken]

I would create a swarm monster for the creatures, and consider the influx of reinforcements as healing for the swarm. Ideally you want to run the entire battle out, because if the goal is to get the McGuffin and get out, they might simply take the damage and leave, rather than trying and fight off everything. Make sure you use words like "endless horde" and "fanatical zealots" to give a sense that this be the best option.

If you want to quickly determine the fight, ask the party how much they want to spend in resources for the fight. Determine the PC damage based on the average damage by the swarm (to all PCs in the open, or the front line in a choke point) and the average damage done by the party each round. You might want to ask for a HP threshold for them to change tactics, so that if a PC looks weak, they can switch things up (possibly healing). You can then calculate damage for each group until the battle is over, or the HP threshold is reached.

 

[Oofta]

I generally just use mob rules, although I may also throw some other checks using various skills. I'd also consider adding morale checks for the enemy.

Give the PCs options for things like setting up distractions, stealth, misdirection and so on. In order for this to be fun, I think you're going to have lean a lot on imagery and descriptive text. There's nothing wrong with bits of the encounter being a bit of a slog up to the point of proving how difficult this is. At a certain point, you may want to make sections a simple challenge and simplify combat with a handful of rolls on each side.

But also give them avenues to change the flow of the mobs, avoid them or simply hide in a corner as a massive group goes by. Good luck!

 

[pming]

Hiya!

I 'created' a Zombie apocalypse game/setting using the old "Top Secret/SI" game system back in 2010'ish? Anyway, "Zombocalypse", as I called it, dealt with 'hoards' of zombies rather well. I was pleasantly surprised at how well my rules worked, so here they are. I'll 'convert' to D&D terms after...

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Zombie Hoards​

One zombie is one zombie. Two is a pair. Three, a trio, Four and five are "four or five zombies". Six is "half a dozen". Between 7 and 1O is a "small group". Once you hit 11 — 15 you have found a "large group". And before you ask, no, there is no "medium group" of zombies...its small, large or.... When you hit more than 16...you have yourself a zombie-hoard. Zombie Hoards range from "small" (20 to 30), to “pretty big” (30 to 50), up to “OMFG WE ARE ALL GONNA DlllllEEEEl!!!!” (at 50+).

If you find yourself fighting a zombie hoard, things are looking grim. If you go down during a zombie hoard, no amount of Luck Points will save you. You are immediately set upon by the ravenous dead and devoured. Even as little as "four or five" zombies will spell your end, regardless of Luck, if nobody is around to save your ass. That said, one to three zombies...you can Luck out.​

Hoard Mechanics​

A zombie hoard functions as a "single entity", more or less. The average CON of the zombies involved is used, rounded up to the nearest 10. They all move at the MOV of 20 (unless they "Surge"; see below). If they (PC's) do MORE than the hit points of the average zombie in the hoard (re: CON / 10), they kill one zombie. If the character does LESS than the hit points of the average zombie, the zombie hoard does NOT loose a member (see below). The zombie hoard still attacks that character (if they are up close enough), and they still advance as if nothing happened (re: they move 25). To put it another way...the march of the zombie hoard is relentless and brooks no injury to itself until the very last zombie is dead. The GM simply needs to keep track of the total number of zombies and tick them off, one by one, as they go down. Only when the last zombie is dispatched is the "hoard" considered gone (e.g., even if you are down to a trio of zombies, they still count as a "hoard"). Yes, it kinda sucks for the PC's, but this is a zombie apocalypse...it's not supposed to be fair!​

Surge​

Each round, the player can attack the hoard. A zombie hoard can surge each round. A surge is when they get pushed ahead from more, uh, pushy zombies in the back. Or, maybe new zombies come out of the back room...or out from behind an overturned bus...or from the bushes...or, hell, crawl up out of the freaking ground! The point is, each round the GM rolls 1d10. If the d10 comes up the same as what any PC‘s initiative die was, the zombies surge; the zombies move at least twice as fast that round (roll another d10; if it's any number other than what was used to Surge, they move at double...but if it's the same number again, then it's triple!). Whats worse, is that whatever the 1d10 result was, that's how many new zombies are added to the hoard. If the PC's are in a heavily populated area (re: a big city or the centre of town), you can DOUBLE that number. (moral of the story; if you need supplies from town, don't send ‘everybody‘...small and quiet is probably better...maybe...ish...).

Additionally, if the PC's are making a lot of noise (re: using guns, chainsaws, cars, etc.), double the number surging. So, if a tie initiative roll of 6 comes up, that's 6 more zombies. If that happened in a downtown area, make it 12 new zombies...oh, the PC's are using shotguns? Double it again, to +24 zombies. Zombies show up within the number rolled X10’ (ex: 6 tie = +6 zombies which appear within 60'). Generally, half of them will be within half of that. That is also a radius; those 6 extra zombies could have 2 directly in front of the PCs, 1 comes from the right side of an overturned bus, and the last 3 are actually right behind the characters...in the supposedly locked drugstore they were backing up towards to try and get some cover... (the GM is encouraged to be devious here...not unfair...but definitely devious...).
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So there you have it. The "CON" thing is TS/SI's version of "Hit Points", basically (although they do use locational HP's; my zombies don't though, fyi). The "d10 for Surge stuff" is the equivalent of an Initiative roll for 5e."MOV" is their movement score; I'd say a MOV of 20 is about the same as a 5e Move of...10? Maybe 15'? Hmm...maybe even just 20' and leave it at that.

How I'd use this for 5e is similar. I'd have the "hoard" have an 'AHP' (Average Hit Point) buffer...think of it like a DC to kill, but using a PC's Damage total as the 'ability check'. So if the Frog-Men hoard had an AHP score of, say, 10, then anytime 10 or more damage was done to the Hoard, 1 Frog-Man would die. If a PC swings and hits, and does 23 points of damage...he killed TWO Frog-Men. Simple. Keep the AC thing as per 5e. I'd then simply increase the Frog-Men's "Hoard Total Members" by X amount each round (probably based on their distance to the 'hoard origin source'...the closer they are to it, the more Frog-Men pop out each round).

For PC's with spells/abilities relying on, hmm... "specific locational/situational details", I'd just assume "Yes, you have it". In other words, a Rogue can use his Sneak Attack every round, for example.

Anyway, that's my Zombocalypse rules that I created and used to great effect for our zombie game I ran all those years ago. Maybe they can be tweaked or give you inspiration for something.

^_^

Paul L. Ming​

 

[MNblockhead]

Years ago I tackled this question for a 4th edition party running through Dragon Mountain which featured lots of kobolds. Like you, I was looking to allow for some familiar strategies of fighting a monster to feel relevant while also offering more opportunities for interesting challenges & creative lateral thinking. Besides minion rules and a bunch of other devices, I created a Kobold Horde stat block which emphasized unusual ways of interacting.

It had the following traits (translating for 5e parlance):

• From All Sides: The kobold horde occupies an enormous undefined area, and it can move into and through enemies' spaces and does not provoke opportunity attacks. It is considered adjacent to all enemies in the encounter at all times, and has advantage on melee attacks thanks to Pack Tactics.
• Swarm Attack: At the start of each of the kobold horde's turns, all hostile creatures in the area are grappled (escape DC #). A creature starting its turn grappled by the horde takes 5 bludgeoning damage.
• Horde Immunities: The kobold horde is immune to all conditions that don't originate from area effects. If it would be incapacitated, the swarm instead lets go of the nearest grappled creature.

It also had the following actions/bonus actions/legendary actions:

• Overwhelming Surge: The kobold horde makes an attack against each creature in the area. If a creature has been disarmed of a magic weapon, then one of these attacks is made with that weapon.
• Swarm the Fallen: The kobold horde targets each prone creature in the area with a special attack that disarms the creature of a held item.
• The Horde Presses Down: Each creature in the area must choose once check to make (DC X) to resist the horde: Athletics, Perception, Stealth, or Survival. A failed check indicates that creature has been separated from the rest of its party, in addition to the following:
  • If the creature fails Athletics, it is restrained until the end of its next turn and the kobold horde gets a free attack against it.
  • If the creature fails Perception, it is forced into a trapped passage (roll on Random Trap Table) until the end of its next turn.
  • If the creature fails Stealth, any light source it has is lost and it is forced into a dark passage until the end of its next turn.
  • If the creature fails Survival, it is forced into a tight passage until the end of its next turn – its speed is halved and attacks against it have advantage due to squeezing, and its attacks with non-Light weapons suffer disadvantage.

Wow, love it! Could you share the entire stat block? How did attacks work? Could the horde attack more than one party member per turn?

It doesn't really handle the trickling stream of near unending monsters but this will take care of most situations other than a few edge cases. I'm really liking the trains and legendary actions.

I'm thinking I would have multiattack with the number of attacks dependent on the number of hit points. E.g. when the swarm is half the size it makes half the attacks.

For some hordes, I might add morale. After losing 1/2 or 2/3 hit points they retreat. But that may be better left to DM role-play discretion (if guarding their home and children, perhaps fight to the death, whereas if a raiding party maybe any display of great strength will send them running to raid software targets another day).

Using legendary actions is really interesting and helps to make if feel more like being caught in a horde.

One last thing I'm thinking of is a trait that says that depending on the number of hit points left on the stat block, the horde auto hits everyone in the group up to a certain AC. Or that the horde starts with an insanely high to-hit bonus that is whittled down as hit points decrease. That more than anything would make hordes truly terrifying. Even characters of great power should fear getting caught up in a mob or horde.

The only downside is that unless you are dealing with tiny or small creatures, I don't know if my players would accept "from all sides" if they are in a confined area. It is still difficult to determine how this will work when the party holds a choke point for example. This is where "The Horde Presses Down" can really come into play. I would further add that the horde can expend a certain number of hit points to give a bonus to the hordes contested skill check to represent sacrificing the lives of those in the front to make an overwhelming push.

Thanks again, this has given me some ideas that I'll definitely will be putting to use.

 

[J-H]

What else is going on at the time?

I used a skeleton swarm in Castle Dracula. The party knew they needed to go forward, so the monk found a nice spot on a narrow stairway and just held off the additional 6 skeletons (unarmed) per round until the ambush ahead was cleared, then used Monk Speed to catch up with the party once they were someplace where they could slam and bar a door behind them.

Spoiler

Of course, it was the room where the Avatar of Death met them, but at least there weren't more skeletons coming.

A swarm like this should be tied to some other obstacle or event going on. If the party can just stand there and shoot a swarm in a barrel all day long, it's not very interesting from a story perspective... unless it's a horde of really challenging creatures and the task is more like "Hold the portal to the Abyss for 30 rounds until the Paladins arrive."

 

[MNblockhead]

Here is a sketch of simulationist mob rules:

D&D 5E - Handling mobs

I really enjoy the use of minions in 5e, but like the sane, rational person I am, I don't want to deal with each individual minions attack and damage rolls. I also don't like the exactness of the DMG's rules for handling large groups of enemies. So I've stolen some concepts from the Conan 2D20...

www.enworld.org

you work out their HP/square and have damage/AC/save DCs/etc scale with the number of attackers in a pretty simple manner.

HP damage instead kills squares of it. You don't track individual monster HP, just squares. And you round HP/square to something nice.

When someone throws a fireball that hits 20 squares of it, you roll 8d6*20 and give them a +10 (+1 per square beyond the first, capped at +10) save bonus (this represents that the ones in front give cover to the ones behind). They pass (naturally) and take 8d6*10, or 280 damage. If they have 20 HP/square, that is 14 squares dead.

Similarly, their attacks are massed; every doubling of attackers gives them an extra set of damage dice, and they get +1 to hit for every attacker beyond the first (up to +10).

So if you are surrounded by 8 of them, they get +7 to hit and deal 4[W]+stat damage on a hit.

In this model, players who want to fight it have to actually fight it, but we reduce interaction to 1 roll per interaction, instead of 1 per monster.

A fun part of this is you can simulate infinite hordes this way; like a wave of zombies. Each entrance has a number of zombie squares/round incoming (based off a choke point and how fast they move). Killing them just pushes back the wave by a certain number of squares.

Nice! Another great idea I'm going to use.

A mixture of horde stat blocks and this HP/square idea will really help. I like how saves and morale works.

One thing I need to think about, which I might change is the to-hit bonus. If someone is surrounded by Zombies...not just 8, but a horde pressing in, even a +11 means you need to roll over 10 to hit most well armored fighters. Not sure how I want to tweak it. Maybe if you are are surrounded completely, they auto hit. If you are flanked the hit is at advantage.

Also, if you have the party surrounded with the mob around them and between them do you roll for the mob to hit more than one player per turn? I'm thinking I would not give the mob initiative. Instead I roll to hit for the mob at the end of each players turn. Give the character an opportunity to move to a better location or decrease the number of attackers (hp per square). E.g. the mob auto-hits or rolls to hit after each characters turn if that character is adjacent to at least one mob square.

While I like the "horde" for more powerful and intelligent mobs, esp in more open areas or TOM play, the HP per square rules is great for the stream of monsters issues I rose in the OP. Also great for large numbers of weak minions and very easy to put into play with very little prep. Also easy to use with a VTT.

I'm thinking a mix of the two approaches could work well. HP per square, indicating mob-controlled sqares but also total HP tracked on mob stat block and add some of the traits and actions discussed in other posts.

This is already making me excited about running mob encounters. Thanks guys!

 

[MNblockhead]

It can if we make a few tweaks.

Echoes some of the other posters ideas. Good stuff.

3) As new dudes enter the room, add another swarm, or simply "heal" the existing swarm and then fill back in the squares.

Brilliant idea! Love it!

 

[Oofta]

Instead of thinking of "from all sides" change it to people being pushed around or knocked prone. A mass of bodies is going to be far more effective than a single individual at shoving, although of course you don't want to overdo it either.

I vary the actual numbers I use based on scenario and monster, but a baseline I have used is that I go up to a 20 strength and (again depending) give the monster advantage on the shove attack. Think of zombie movies where the horde is like trying to stop an avalanche. It's not just the guy in the front line pushing, it's the dozens of guys behind them also pushing.

Once someone is prone they can be dragged into the mob as well, but again when I did that it was zombie hordes.

If it's more intelligent monsters consider giving the back ranks reach weapons and ranged attacks that get fired in volleys.

 

[CapnZapp]

I can't believe nobody has brought up Spirit Guardians and similar effects.

Before having any discussions like this, first make sure the party cleric (etc) doesn't have access to these spells.

Because if they do it's just game over: any monster that comes at you in great hordes must by definition be weak enough to die to the aura.

This kind of spell is simply created by a developer who hates the trope you're trying to enact here.