How to Run Monster Hordes in D&D

Aug 13

How do I run Monster Hordes in D&D?

How about pitting them against the creatures of hell flooding in through a rift? Well, today we teach you how to do just that. Join us as we share How to Run Monster Hordes in Dungeons & Dragons.

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It’s worth noting, that the 5e Dungeon Master’s Guide does offer detail on handling hordes in chapter 8 “Handling Mobs”. But, it doesn’t do a particularly good job in my opinion. All it really does is give you a small chart based on the d20 roll and the number of the attackers. It just indicates how many hit, and you just add the damage. It certainly does make it a bit quicker. It also mentions that “Keeping combat moving along at a brisk pace can be difficult when there are dozens of monsters involved in a battle. When handling a crowded battlefield, you can speed up play by forgoing attack rolls in favor of approximating the average number of hits a large group of monsters can inflict on a target”. This is pretty great advice in general.

But the rules are lacking, and I think there is a better way to handle it.

A real simple way is to decide the size of the horde, and treat each minion as if they go down in a single hit. Maybe allow elite soldiers to go down in two hits and just focus on the narration. To really get the feel of a large-scale battle you could even toss in the lair and legendary action-like effects. I think siege equipment and powerful mages are great for filling these roles.

While this is certainly a better approach, these are kinda lacking and not fleshed out. Honestly, it still leaves a lot of DM fiat (which isn’t necessarily a bad thing). So we are going to present you with a new alternative. Something a bit more constructed, and more or less simpler to run as a DM.

Instead of trying to track dozens or even thousands of individuals, we will focus on leveraging the swarm mechanic that already exists within DnD. Here are some details from the swarm of rats.

Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for two wagons. The swarm can't regain hit points or gain temporary hit points.
Bites (swarm has more than half HP). Melee Weapon Attack: +2 to hit, reach 0 ft., one target in the swarm's space. Hit: (2d6) piercing damage.

This simple ruling combined with huge or gargantuan sizes can make any group of enemies into a single stat block for tracking purposes, but give us the feel of a massive horde of enemies.

The swarm feature itself however isn’t going to be enough. We will have to add onto the stat block a few other mechanics that really make it feel like a large-scale horde of enemies attempting to “swarm” (see what I did there?) your heroes.

There are a lot of benefits of the swarm mechanic that really apply well.

First, it makes it less cumbersome on the DM.

Second, the swarm or, in this case, horde, has special immunities against a variety of conditions, such as charmed, frightened, grappled, paralyzed, petrified, prone, restrained, and stunned. Which fits the horde theme perfectly. Most spells that target these conditions, usually only affect a single target. So it makes sense that overall, they wouldn’t impact a horde.

Third, it provides a progressively weakening attack as the swarm loses its hit points as well as having a shared AC. We can think of this as the horde getting weaker. This is handled in a way that the swarm creature does less damage at half its hit points. I’ve found that changing the damage die size allows me to play more in the area of quarter health. For example, a horde might start at a d12 damage die. When it reaches < 75% I reduce it to a d10, then at <50% a d8, and so on.

This simple change is a great start. But, we really want to add a few more mechanics to make it feel like a massive horde. I’ve found that adding the following features really can help with this. For our horde, let’s assume it is a large band of bandits.

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Since our horde by default can attack any creatures it shares space with, giving multiattack is a clear starting point. This allows the horde to attack multiple creatures at one time within reach, or within their space. We can also assume that we can freely change the damage type of weapons between piercing, slashing, and bludgeoning. This simple fact is, that they probably aren’t all wielding the same weapon.

Next, we want to be able to include special effects. Since we are discussing bandits. They may have special explosives, traps, spellcasters, or just a set of randomly loosed arrows or bolts. How can we represent the chaotic element with just a single monster stat block? Simple, we use the Lair action system 5e has so kindly developed for us.

What we use really depends on what we are trying to capture. If we assume we want the focus on the loosed bolts and arrows, then we know we need an area of effect type saving throw or multiple attack rolls. The adult white dragon has a great lair action that will fill this role.

Jagged ice shards fall from the ceiling, striking up to three creatures underneath that the dragon can see within 120 feet of it. The dragon makes one ranged attack roll (+7 to hit) against each target. On a hit, the target takes 10 (3d6) piercing damage.

All we have to do is change the text slightly and BAM! Instant Lair Action for our horde.

A barrage of bolts and arrows fills the battlefield, striking up to three creatures that the horde can see within 120 feet of it. The horde makes one ranged attack roll (+7 to hit) against each target. On a hit, the target takes 10 (3d6) piercing damage.

The last mechanic can help our horde make a variety of actions that may be outside of just damage. We can utilize the legendary actions to fill this role. Below are a few examples that really feel like a horde. Continuing the bandit theme, we may have some sort of leader that could issue orders. This could be done really well as legendary actions. The simple act of taking the Dodge Action (which is strong and certainly should consume the majority of the cost of the legendary actions) can be a powerful tool if the characters are dealing great damage to the horde.

Other options may include something like stampeding over the characters when the horde moves.

Stampede. When the horde moves through the space of a Large or smaller creature, the horde can force the creature to make a DC 15 Strength saving throw. On a failed save, the creature is knocked prone.

The legendary action is also the place to include details for special creatures in the horde such as spellcasters. This could be an AOE effect such as fireball, or even a healing effect like mass cure wounds. In either case, it gives the illusion of a grand-scale battle.

This is a great way to give the feel of the push and pull of dozens or hundreds of enemies in a battle.

Beyond the building of these mechanics, it’s important to remember there we need to be flexible when the characters try certain features or spells. For instance, a character who wants to cast a fireball on the horde is going to be different than something like shooting a single arrow. We recommend using the vulnerability and resistance system for this and tying it to the creature’s hit points. For example, at full health, fireball is certainly going to hit a lot of enemies, so we can justify giving it vulnerability. But, once the horde is less than say half hit points, it may just be regular damage, and then resistance when they have less than 25% hit points remaining, as there are fewer targets clumped together. This is a light ruling, and may require DM fiat, but is certainly a way to reward those powerful AOE spells, without making the player feel like their most powerful effects seem dull in the battle with a horde. Using the resistances and vulnerabilities can really balance the scales, without punishing or rewarding one particular group of play styles over the other.

What do you think? Would you use this style of combat to run your hordes? What are some styles you’ve done that you’ve had success with? We want to know. Come and tell us on our social media @critacademy

Related Articles: How to Run D&D Combat that Flows

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Unearthed Tips and Tricks

D&D Monster: Gajah Warrior

Origin: minotaur

Lost Features:

Powerful Build. The gajah counts as one size larger when determining its carrying capacity and the weight it can push, drag, or lift.

Trampling Charge. If the gajah moves at least 20 feet straight toward a creature and then hits it with a melee attack on the same turn, that target must succeed on a DC 14 Strength saving throw or be knocked prone. If the target is prone, the elephant can make one stomp attack against it as a bonus action.

Multiattack: Gajah can make two greataxe attacks.

Greataxe. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 10 (1d12 + 4) slashing damage.

Stomp. Melee Weapon Attack: +6 to hit, reach 5 ft., one prone creature. Hit: 20 (3d10 + 4) bludgeoning damage.

Reactions

When a creature scores a critical hit on the gajah, it can use its reaction to release a deafening thunderclap from its trunk, audible out to 500 feet. Each creature within 60 feet of it must make a DC 14 Constitution saving throw. On a failed save, a creature takes 14 (2d12) thunder damage and becomes deafened for 1 minute. On a successful save, a creature takes half damage and isn’t deafened.

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D&D Encounter: The Mad Orc

The party has been told to investigate rumors of a mad orc wandering an ancient battlefield; there’s evidence he’s preparing some ritual at one of the mass graves there. While no one is sure what, they’re convinced it’s for evil.

Yorric has no ill intentions and simply wishes to fulfill his dream of being an Elephant herder. If left alone, Yorric will start herding a hundred Skelephants from battlefield to battlefield and “clean up” the mess by having them “graze” there.

As the party comes upon the scene, Yorric has started his ritual, a Maelstrom of necrotic energy is beginning to gather over the mass grave, and he carefully harnesses it into the bones, his face scrunched up in concentration.

Yorric is flanked by two huge Skelephants, Bill and Billy, wearing crude barding (AC 16) that provides full cover to their skeletal cargo, protecting them from attacks from outside the ribs.

Bill carries four skeletons armed with pikes, and Billy carries four armed with longbows.

If attacked, Yorric will focus on the ritual while Bill and Billy protect him. At the start of each round, roll a DC 14 Wisdom save for Yorric; if he fails, he gets distracted by the battle, and Bolts of necrotic energy strike out at random creatures, have everyone roll a DC 15 Dex save or take 2D8 necrotic damage on a hit, undead get healed by the damage they Take. Every five rounds, Yorric is uninterrupted. A Skelephant rises from the grave and wonders off in a random direction unless attacked; then, it joins the fray.

For their stats, take the elephant Stat block, make it undead, reduce their HP by 30, give them vulnerability to bludgeoning and Radiant, Immunity to necrotic and poison, as well as the poisoned condition, and reduce their attacks damage by one die each and there you go, a Skelephant

D&D Magic Item: Crackling Great Maul

Weapon (maul), legendary (requires attunement)

You gain a +l bonus to attack and damage rolls made with this magic weapon. It is sized for a giant, weighs 300 pounds, and deals 3d12 bludgeoning damage on a hit, plus an extra 2dl2 bludgeoning damage to creatures at least one size smaller than you.

The maul sheds green light as a torch when dragons are within 1 mile. The light can't be shut off in this condition.

As an action, you can cast a version of the scorching ray spell (spell attack bonus + 8) that deals lightning damage instead of fire damage. Once this power is used, it can't be used again until the next dawn.

D&D Dungeon Master Tip: Better Monster Knowledge Checks

When it comes to sharing knowledge with the players about monsters, we as GMs typically choose to call for some sort of intelligence check, or just directly inform the players what their characters know. This can sometimes feel a bit bland or binary during the game. If we consider knowledge checks to be more of a range band, we can significantly increase the narrative of monster knowledge as it pertains to the player characters.

In a fantasy world, superstition and misinformation are common. This is particularly true over long distances. Details, rumors, and understanding of monsters also change between groups. For instance, commoners likely have less understanding and information than merchants who travel, or nobles who have guards and aren’t put into situations where they must engage directly with monsters.

We know adventurers are certainly more informed on monsters than most. But that doesn’t mean they know everything about a monster's skills, weapon techniques, weaknesses, strategy, etc. So, how do we capture this variation with a knowledge check? Well, instead of setting a single DC, such as a DC 15 Intelligence (Arcana) check to learn what knowledge a character knows about mephits. In this case, if they fail, they may only learn that a mephit is an elemental creature. But a success may reveal the mephit is a magma mephit from the elemental plane of fire and can breath fire.

If we look at monster knowledge checks as a range band, instead of just a success or fail, we can expand how much knowledge is known based on the value. If we set the range from 5-30, we can make a knowledge check progressive.

< 5: The character has never heard of such a creature, or just out right misidentifies it.

< 10: The character knows rumors, some of which are inaccurate.

< 15: The character can accurately identify the creature as well as some of its most iconic features or traits.

< 20: The character is well educated on the creature, its features, traits and perhaps some immunities or resistances.

< 25: The character has an advanced understanding of the creature's culture, history, features, traits and even weaknesses.

< 30: This range should be used for unique creatures and reveal every detail of the creature and its existence.

D&D Player Tip: Best Rogue Build: Ultimate Shooter

The core of the rogue's damage comes from sneak attack. The feature itself is powerful but requires special conditions to achieve. Well, with the steady aim feature from Tasha’s Cauldron of Everything, we can ensure not only can the rogue get sneak attack EVERY time, but from range and avoid taking damage.

Steady Aim, allows rogues to use bonus action to grant themselves advantage on their next attack roll. The only issue is they can’t move before or after the use of steady aim that turn. Advantage on attack rolls AND sneak attack? Yes, please! Though, we still can’t move at all. Makes it dangerous.

If they are mounted, they can take the steady aim and still move, since the movement is that of their mount. So how do we get them a mount? Not every DM will make a mount available. Well, the Ritual Caster feat allows the character to pick up the Phantom Steed spell from the wizard’s spell list. This allows you to spend one minute summoning a spectral steed that can move up to 200 feet per round. Now, enemies can’t catch us, we nearly always have advantage (or offset disadvantage) and get our sneak attack.