Tips on running mass combat smoothly

[Lye]

One of my players told me the other day that he really like doing mass combat. Luckily for him, he's just alerted an excess of 300 undead and evil plant creatures to his location and they will be attacking the party as soon as they leave the palace they've been plundering.

Under normal circumstances, I never would have done such a thing, but I'm running a setting for us as it's written and this was the result of stealing from the long-dead queen of the palace.

I'd like to know if any DMs out there have any tips or tricks they use for handling massive combats like this without them becoming an uneventful slog through a mass of HP that just never stops.

[mabriss lethe]

One of the smoothest ways to handle it is to have the mass combat be happening in the background. The adventurers continue to fight at their normal scale. Plan the basic flow of the battle out as a "What's going to happen without interferrence" scenario. Then let the players loose to alter the flow of combat.

Assassinating a captain might make a charge fall apart that should have broken the players' allies, but it also means that a group of saboteurs makes it through to one of the gates. If the players hurry they can secure the gates again, letting the reserves mop up the invaders who broke through. But if they don't make it in time, The enemy holds the gate and they might find themselves having to lead a street by street withdrawal back to another position, and then later having to provide a distraction so that their allies' main force (the ones saved by assassinating the captain) can drive out the invaders and then retake the gate.

[Karl Aegis]

Round hit points and damage to the nearest 5 like they do with the minis. Roll to hit and deal automatic damage.

[Uncle Pine]

One of the smoothest ways to handle it is to have the mass combat be happening in the background. The adventurers continue to fight at their normal scale. Plan the basic flow of the battle out as a "What's going to happen without interferrence" scenario. Then let the players loose to alter the flow of combat.

Assassinating a captain might make a charge fall apart that should have broken the players' allies, but it also means that a group of saboteurs makes it through to one of the gates. If the players hurry they can secure the gates again, letting the reserves mop up the invaders who broke through. But if they don't make it in time, The enemy holds the gate and they might find themselves having to lead a street by street withdrawal back to another position, and then later having to provide a distraction so that their allies' main force (the ones saved by assassinating the captain) can drive out the invaders and then retake the gate.

This is a great advice if the mass combat happens to feature two or more armies fighting against each other. However, it seems to me that in this case it's more like 300 enemies between undeads and plants Vs 4-6 PCs.

A few suggestions:
- Roll a lot of dice beforehand. Compile the results into a .txt and use them whenever the many enemies roll to-hit, deleting results as you go. It's a boring suggestion but it's going to speed combat immensely.
- Keep in mind that even if there are 300 enemies, PCs won't deal with all of them at the same time: if four Medium PCs stay in a tight square formation there are only 12 squares adjacent to them. If they scatter a little there will be more, but keep in mind most creatures (especially unintelligent undeads) aren't extremely efficient stategic geniuses it's likely there will always be some empty squares, reducing the amount of rolls you as a DM have to do each round.
- Related to the above, it's plausible that some nonadjacent enemies will be armed with reach or ranged weapon. It's unlikely all of them will.
- Also related to the above, keep the flow of the battle dynamic. If the characters are trying to get from one end of an army to the other and are successfully chopping heads around, they should move at a reasonable pace. Don't be afraid to describe openings whether they're already there or appear after chopping a large skeleton ogre or a corrupted treant. No army of enemies is a 100% efficient living wall where a downed foe is immediately replaced. Unless it's a Living Wall (Dragon #343 p48).
- Keep ranged enemies down to a reasonable amount. This is repeated twice because it can seriously affect the amount of dice you need to rolls each turn.
- Aid Another can be used to trim down the amount of rolling, as well as ensuring the giant brute in front of the party using Power Attack actually hits. But your main concern should be not having to roll the various critters' huge amount of attacks that will invariably miss.
- There are teamwork benefits other than the ones described in Heroes of Battle which can be used to have a group of ranged/melee characters use a single attack roll to hit as a single entity instead of attacking individually. It's not in Heroes of Battle though, so unless you or someone else can remember them existing somewhere is of little use. Worst case scenario you can use arrow volley attacks from Heroes of Battle (but those aren't the ones I was thinking about).
- Condense some of the enemies into mobs (DMGII) for a nice change of pace.
- Don't have the fight happen in an open, featureless plain. Players should have some terrain features like big rocks, scattered trees, maybe even marshes or Thermopylae-style valleys (depending on where exactly this palace was located) to toy with, or to be punished for not taking advantage of if you feel like it.

[Lye]

- Also related to the above, keep the flow of the battle dynamic. If the characters are trying to get from one end of an army to the other and are successfully chopping heads around, they should move at a reasonable pace. Don't be afraid to describe openings whether they're already there or appear after chopping a large skeleton ogre or a corrupted treant. No army of enemies is a 100% efficient living wall where a downed foe is immediately replaced. Unless it's a Living Wall (Dragon #343 p48).

Nice.


- Condense some of the enemies into mobs (DMGII) for a nice change of pace.

Oooh. I remember reading that once upon a time. Definitely worth a second look.



- Don't have the fight happen in an open, featureless plain. Players should have some terrain features like big rocks, scattered trees, maybe even marshes or Thermopylae-style valleys (depending on where exactly this palace was located) to toy with, or to be punished for not taking advantage of if you feel like it.

Vampiric Treants are a thing here, so for whatever stupid reason, the trees are alive and literally trying to kill them.

Thanks for these suggestions.

[Darth Ultron]

The most basic advice here would be: Don't use D&D for mass combat.

There are a ton of mass combat games out there. Pick one and use it for the mass combat.

Cry Havoc is a d20 mass combat book. There is Mongoose's Open Mass Combat System. Warpath from Adamant Entertainment.

The AD&D Battlesystem rules are ancient, but do work.

I myself have always used the The old D&D Cyclopedia "war machine" rules.

[Zollqir]

Pathfinder has good rules for mass combat from the Ultimate Campaign book.

Alternatively, consider looking into Pathfinder's [troop] subtype from Bestiary 6. Troops work similarly to swarms, but are comprised of small, medium, or even larger creatures.

[Elkad]

In some ways 300 creatures is easier than 30. Because you can get away with just using statistics for blocks of creatures doing the same thing.
20 of them get every roll from 1 to 20.

"40 skeleton archers shoot at each of you. Joe, they need a 17 to hit you, so that's 8 hits. 2 of them are threats, I'll attempt to confirm manually - dice clatter - nope, so 8d8+8. That's 44 average, or you can roll damage against yourself."