5E My homemade 5th Edition Mass Combat Rules (Based on Handling Mobs)


This is a system I just came up with, and I want to hear your thoughts.

Basically, I take the rules of "Handling Mobs" in DM Guide page 250, and expand on them a little.

My design is the following:

An army has a total of hit points based on Monster HP x Number of soldiers.

The army has five stages of effectiveness, based on the amount of hit points. The effectiveness is a multiplier which affects damage per round.

100% effective = full hit points
75% effective = total hit points down to 3/4
50% effective = total number of hit points down to 2/4
25% effective = total number of hit points down to 1/4
0% effective = army destroyed
NOTE: A change in effectiveness takes place in THE BEGINNING OF THE NEXT ROUND!!

Each round the army chooses how to attack, based on a regular / unique attack it has.
Damage is multiplied based on how many soldiers hit.

Repeat each round until an army is routed or destroyed.
Note: An 'army' which is composed of a single unit, i.e. the Tarrasque, has no penalties for lesser effectiveness, and always hits once, regardless of enemy AC.


An army of 50 guards attacks an archfiend to protect their city from demonic invasion. Initiative is rolled, and the guard army goes first. The guards have 16 hit points each, giving them a total of 800 hit points. The Archfiend is a single monster with 400 hit points.

The guards need a 20 to hit the archfiend (because it has an AC of 23). Based on the Handling Mobs rules, this means that 1 out of 20 guards hits the monster this round. Since the guards are 100, this means that the multiplier for damage is x5, and the effectiveness is 100%, which means no penalty. The guards roll 1d8 and get a 6. Multiplied by 5, the guards gave the Archfiend a total of 30 hit points of damage. Of course, considering the fact the monster is immune to normal weapons, the damage is in turn, turned to zero.

On its turn, the Archfiend chooses to use a Mass Fireball spell instead of attacking once in melee. Rolling the dice, the spell causes 200 hit points of damage (theoretically - I'm not even sure if the spell can cause so much damage). The guards roll a saving throw (once, affecting all), and fail, taking 200 hit points of damage, bringing their total hp to a 600. This brings their effectiveness down to 75%.

The guards keep doing their thing and roll 1d8 for damage against the Archfiend. They roll a 4, which multiplied by 5 makes it a 20. However, their effectiveness is down to 75%, which means they get a multiplier of 0.75, bringing their damage to a total of 15 hp this round. Again, all that damage is negated because the damn thing is immune to mere weapons.

The Archfiend makes another Mass Fireball spell and the guards fail their saving throw, taking another 150 damage, bringing their hp total to 450 (still at 75% effectiveness). Or it could use a single melee / ranged attack, or do something else ...

2000 human soldiers vs 1500 orcs

2000 guards (each having 18 hp) give us a total of 36.000 hp (THAT'S A LUTTA NUTS!!) AC 16
1500 orcs (each having 22 hp) give us a total of 33.000 hp. AC 13

ROUND 1 - Guards won initiative
The guards need a 10 to hit an orc - based on the Handling Mobs rules, half of them hit. They roll a 1d6+1 and get a 4. Multiplied by 1.000, this means they caused 4.000 hp of damage to the orcs.

The orcs need an 11 to hit the guards, so they get the same treatment and get half of their units to cause damage. They roll a 1d12+3 and get a freaking 15 - multiplied by 750, to a total of 11.250 hp this round.

The guards are fewer than 27000 (their 3/4 hp total) which means they're now at 75% effectiveness. Their damage will now get a 0.75% multiplier. They roll for damage, get a mere 2, multiplied by a thousand, and then by 0.75 for a total of 1500 hp.

The orcs have a current hp total of 27500, which isn't enough to take them to 3/4 of their hp total, which means they're still fighting at 100% effectiveness. They roll for damage and get a 10, multiplied by a thousand to bring a devastating blow of 10.000 hp to the guards.

The guards have seen much better days ... with their current hp total at 14.750 - less than half hp total, they're now at 50% effectiveness. They get a multiplier of 0.5 each time they do damage.
The guards roll for damage and get a 6, multiplied by a 1000 and then a 0.5, to total of 3.000 hp.

The orcs (still at 100% until the next round), attack and get an 8. Apparently, Gruumsh favors his sons this day, to a total of 8000 hp of destruction.

The guards are a shadow of their former fighting strength, with a mere 6750 hp pool, less than 1/4 of their total hp - they're now down to 25% effectiveness, giving them a penalty modifier of 0.25. They make a desperate attack at the orchish horde and roll a 4, causing them a total of 4x1000x0.25 damage, which translates to 1000 hp. In short, they're screwed.

The orcish horde has FINALLY began to weaken, with a hp current total of 24500, which is (by an inch) less than 3/4 of their hp total. They're down to 75% of effectiveness. They roll for damage and get a terrifying 11, multiplied by a 1000 and then by 0.75, to a total of 8250 hp. This surpasses the current max amount the human guards had - the human army is completely butchered, down to the last man.

Remaining orcs: The orcs began at 33000 hp and finished at 23500, which means that out of 1500 orcs, only 1068 remained (divine the remaining hp total with the hp an individual orc had). The horde feasts on meat and wine as they celebrate their victory during the night and honor their fallen comrades.
So, what do you guys think? Does this system work?


Dusty Dragon

1: clean up the math a bit - is there 100 or 50 guards in your first example? And you have to figure out how area of attacks work vs an army.

2: When two army face each other, not everyone in the army gets to attack. There are guys in the back essentially - only the front line gets to participate.

3: Why do you assume "average" to hit rolls but not average damage rolls? I agree that randomness is good, but it seems a bit arbitrary.

4: How long are these rounds? A battle between 2 large army is over in less than 30 seconds? This is related to problem #2.

I would recommend you look at post #7 on this thread http://www.enworld.org/forum/showthread.php?471525-Tools-for-Running-Larger-Battles-Efficiently#ixzz43z2QJaRu exploder wizard had an excellent quick system.


Thanks for taking the time to comment on this. This is a very rough draft I'm thinking about, so the armor has more than a few chinks.

#1: Yup, that's a typo on my part.

#2: For simplicity sake.

#3: Because that's how Handling Mobs worked in 'to-hit' situations. Based on the enemy's AC and the attacker's +x value, the number of successful attacks is automatically calculated. But I want damage to have randomness, otherwise an army who has an hp advantage is almost sure to win.

#4: I know it isn't realistic, but realism isn't really what I'm going for here. Still, you've got a point. Thanks for the feedback.

DM Howard

This is interesting and I will have to give a try in my upcoming Mystara campaign. Usually I have opted to use an extended skill challenge to adjudicate large battles and sieges.


I'm going to look at this more thoroughly when I get home. 3E and 3.5E stuff works well in 5E with minimal changes, so this should work well. It's a thing I'd like to use in my games too.


I thought the mob rules worked differently then what you have here? I thought they worked more as monsters with some different flavor?

I would totally change your attacking formula. It's kind of complex and it works totally different then other attacks. My idea is that an army gets to make an attack vs everyone next to it. On a hit they deal full damage, on a miss they deal half. Attacks would be considered area attacks, so evasion comes into play and armies take double damage form arena attacks. (Some armies could get arrow volley attacks that are a simple aoe attack like a fireball, and you could make up all kinds of attacks to represent different military moves like a charge, or a encircling.)

You don't want 4 different levels of damage. I say just do one at half HP that drops their damage output and maybe includes other effects based on the kind of army. A orc army might actually get more deadly when they are at half HP for example.


Excellent system! I would only use it to figure out battles where the PCs don't play a huge role. This type of system doesn't give the players a lot of agency but, if they are low level soldiers or not in the battle at all then, that's not necessary. I can see this being used to determine how the whole army reacts as opposed to just the PC's actions. It seems easy enough to make some additions to it to make different tactics to allow more dynamic play. How would you edit the system if a PC was leading the army?


I will probably update the rules tomorrow and give it a more concrete feel - although most of the things that annoyed you guys are still there. As for the math, I don't think it's really hard if the army owner has an army sheet which has the amount of hp at 100, 75, 50 and 25 percent accordingly. And with a calculator in hand the army attack is resolved quite fast (though I admit, by mere human memory it can be daunting and unfriendly). I really don't want to throw away the dice roll or the effectiveness values (the dice adds tension to the attack and the Effectiveness rule is a good tool to make you want to preserve a particular friendly army unit or egg you to quickly take out an enemy one).

Again, thanks for all the cents!


How would you edit the system if a PC was leading the army?
I will write about this tomorrow - basically the PCs and the monster commanders are called VIPs, they possess the ability to find and take out particularly troublesome units or be a tool to roleplay a particular type of encounter (i.e. have the PCs go and sabotage the ballista of the hobgoblin army in order to take it out from the rest of the fight).

Taking out the Enemy Commander forces the army to roll a d12. On a 1-6, the army retreats with lost morale. On a 7-12, the army stays and fights, but the Hit Probability Table for all attacks goes one (maybe even two) step(s) down as a permanent penalty for the rest of the fight. For example, the orcish horde above can hit the human guards as in the '1 out of 2' category. With their commander killed, they would automatically fall to '1 out of 3' (or '1 out of 4') category. This imposes a respectable penalty to the enemy army which makes the death of the commander a legitimate strategic move.


I will write about this tomorrow - basically the PCs and the monster commanders are called VIPs, they possess the ability to find and take out particularly troublesome units or be a tool to roleplay a particular type of encounter (i.e. have the PCs go and sabotage the ballista of the hobgoblin army in order to take it out from the rest of the fight).

Taking out the Enemy Commander forces the army to roll a d12. On a 1-6, the army retreats with lost morale. On a 7-12, the army stays and fights, but the Hit Probability Table for all attacks goes one (maybe even two) step(s) down as a permanent penalty for the rest of the fight. For example, the orcish horde above can hit the human guards as in the '1 out of 2' category. With their commander killed, they would automatically fall to '1 out of 3' (or '1 out of 4') category. This imposes a respectable penalty to the enemy army which makes the death of the commander a legitimate strategic move.
If you stat out the armies a monsters which is what I think you are doing. (It's how the mob rules worked) Then you can easily just have the players engage directly with armies. They can buff them, heal them, attack them, charm them, ect. (Unless you directly stop some actions, but I think you can leave most in with only minor logic bending required.) Also you can just give players their own units to command. Also use smaller groups of people. Like in example two brake up the orks into 6 armies of 250. (Having more then one amy lets you do more tactically too.)


The HP is kind of high. I am workshoping a mass combat idea myself now, but I am kind of running into a issue with how high the HP totals are coming out. Like if you put a 1000 of anything on a field, the total HP is just going to too high to let the players matter or to let the battle not be a huge drag.


Okay, here are the rules in a more complete form:

This is a system to be used for large-scale battles between armies, no matter how many soldiers belong in a unit, how many armies, and what abilities they have.

An army’s health equals to the hit point total of all units belonging to that army. For example, an army composed of 1.000 soldiers with 8 hp each means that the army has 8.000 hit points. When an army loses a large number of hit points, the loss of soldiers translates into lessened effectiveness.

Write down the total number of damage your army receives in a round on the hit point bank. On the beginning of the next round, subtract the number on your bank from your hp total, and reduce the Bank to zero.

An army who loses a percentage of its hp total loses Effectiveness, which in turn lessens the damage the army causes on its turn. There are 5 levels of Effectiveness.
100% Effective = full hit points = x 1 multiplier
75% Effective = less than 3/4 of total hp = x 0.75 multiplier
50% Effective = less than 1/2 of total hp = x 0.5 multiplier
25% Effective = less than 1/4 of total hp = x 0.25 multiplier
0% Effective = hp depleted = army is destroyed

Note that a change in effectiveness takes place at the beginning of the next round, not the round the army unit takes damage (because the army hits and gets hit at the same time).

It’s impossible to perform all attack rolls individually when dealing with an army of thousands, for it is incredibly time-consuming and complicated. Instead, for simplicity sake, use the following rule, inspired by the Handling Mobs rule in the Dungeon Master’s Guide, page 250.

Look up the attack roll bonus the soldier unit of your army has, and compare it with the AC of the enemy soldier who belongs in the opposing army your soldier is attacking. Then, based on the table above, see how many soldiers manage a hit on their turn.

For example, if a soldier needs a 19 to hit an enemy soldier, that means that only one out of ten soldiers manages a hit. Once you see how many attackers are needed, roll for damage, then multiply by the number of total soldiers the army had at the beginning of the battle, then divide by the number of attackers needed, then multiply by your effectiveness meter. That’s the damage your army unit caused the enemy army unit in its turn.

For example, an army of 1000 human soldiers - with a hp total of 8000 hp, since each soldier has 8 hp - is fighting an orcish horde. At the beginning of round 4, the human soldiers have 3978 hp, which is less that 50% of their hp total the army used to have. This means that the human soldiers fight at 50% effectiveness and have a multiplier of 0.5 whenever they cause damage. The human army attacks the orcs. An orc has an AC of 12, and the human soldier has a +3 bonus when attacking with their melee attack. This means that a soldier needs to roll a 9 to hit an orc. Looking at the Army Hit Probability Table, a 9 means that 1 out of 2 soldiers manages to hit the orcs. The player rolls for damage and gets an 8. The army started at 1000 soldiers, so 8 x 1000 = 8000 hp. Then, the damage is divided by 2 (since only 1 out of 2 soldiers hits), reducing the damage to 4000 hp. Then, the damage is multiplied by 0.5 (because the army has lessened Effectiveness) to a total of 2000 hp. The army of human soldiers reduces the hp total of the orcish horde by 2000 hp.

An attack at a disadvantage translates as one step lower in the Hit Probability Table. An attack at an advantage translates as one step higher.

For example, you order your army unit of 12 Trebuchets (catapults) to fire at a hobgoblin army unit when they are 1000 feet away. The hobgoblins have AC 18 and the Trebuchet has a +5 attack roll bonus, which means it needs a 13 to hit the goblins. This means that only 1 out of 3 trebuchets hits. However, since the attack is at a disadvantage (because the attack range of the trebuchet is 300/1,200 ft), the damage is calculated as if it was one step lower (which is 1 out of 4). The final damage roll is 8d10 x 12 (total number of trebuchets), divided by 4 (number of trebuchets needed for one to hit).

An army can have as many units as they like, each army unit acting once in a round. Initiative is rolled individually for each army unit, whether it is friend or foe.

You can merge multiple army units into a single one, or divide one army unit into multiple ones, as long as the army unit is composed of the same creature with the same statistics. Whenever you merge or divide an army unit, the new army unit’s Effectiveness is brought back to 100%, and you divide the new hp total with the hp amount a single soldier has to find out how many troops belong to the new unit(s).

The armies are usually placed on the battlefield the moment an army’s unit can attack another, usually via siege weapons or ranged attacks. Every round an army unit can choose to move and attack, stay its ground and attack, or move twice.

Each army unit attacks just as a singular member of its unit would and its damage is then multiplied by the number of soldiers. This means that creatures who can attack more than once in a single round can do so as an army unit as well (for example, an army of 50 Veterans will attack twice). If an army unit contains a unique character or monster - called a VIP in these rules - that character’s melee attacks are accounted for automatically and absorbed by the army unit he belongs to - these attacks just don’t make a difference.

Spells that target a single creature cannot be used as an attack action by a VIP. Area spells however (such as Fireball), work normally and can be used as a bonus action by a VIP. If an army unit is composed solely of spellcasters (for example, an army of 100 mages), that army can use spells which target a single creature, and then multiply the result by the number of units the army originally had, then multiplied by the army’s Effectiveness. Spells which need a melee attack roll follow the same rules with melee weapons. Each time a spellcasting army uses a spell, that spell wastes a slot for all members of the army.

For simplicity’s sake, and because it is harder to dodge a disintegrateng beam or a fireball when surrounded by troops, always rule that soldiers fail their saving throws. Resistances, immunities and vulnerabilities still apply however.

Creatures with the recharge ability recharge their ability after 3 rounds (if the recharge works on a 5-6) or 6 rounds (if the recharge works on a 6).

A solo creature is a unique monster which doesn’t form an army yet is so powerful it can hold its ground against one. Such creatures are dragons, the Tarrasque, a Demon Lord or other similarly powerful creatures. These creatures ignore the rules of Effectiveness and do not divide their damage via the Hit Probability table. Their immunities also guarantee that they can destroy all but the most powerful of armies.

Multiple army units can occupy the same space (which is then referred to as Enemy Space). For example, an army unit of 60 ogres can fight side by side with a friendly army of a 1000 goblins, each of them attacking individually on their turn.

When an army unit attacks an Enemy Space, the attack can only target one enemy army unit contained in the Enemy Space. If the attack obliterates the enemy army unit with more than enough damage points remaining, the rest of the damage does *not* transfer to other enemy army units which occupy the same Enemy Space.

For example, a human army is attacking an Enemy Space occupied by a goblin army unit and an ogre army unit. The humans decide that the ogres are the greater threat and focus their attack action on them. The ogres have a total of 867 hp and the human attack causes them 1256 hp of damage. The ogre army unit is destroyed, but the goblin army unit is untouched on that turn - the rest of the damage is wasted.

Area-affecting spells are the exception to this rule. The spellcaster(s) who cast an area affecting spell can divide the damage to the enemy army units occupying the same Enemy Space as they see fit. Spells which target a single creature and are cast by an army unit of spellcasters follow the same rules with melee attacks - which means that excess damage is wasted when the target army unit is destroyed.

For example, the Human Sorcerer Cabal casts multiple fireballs at an enemy army space occupied by 100 ogres and 1000 goblins. The attacks deal a total of 1826 hp. The spellcasters decide that 500 of those hp are affecting the ogres, and the other 1326 affect the goblins.

Every army has a commander which issues commands and bolsters morale. This is usually the leader of an orc tribe, a human general or a lich king. While these creatures do not turn the tide of battle through their abilities, their mere presence or demise can shift the balance of the battle. If the commander is specifically searched for by enemy VIPs (a process which can take 1d6+2 combat rounds and needs the army unit the VIPs are members of to physically engage the army unit the Enemy Commander belongs to), a battle between the VIPs and the Commander begins (which is always treated as a Hard Encounter). If the VIPs successfully slay the Enemy Commander, the enemy army rolls a d12. On a 1-6 the army loses morale and retreats. On a 7-12 the army keeps going, but all attacks which consult the Hit Probability table are calculated with one ‘step’ lower.

For example, the orcish army needs a 9 to hit an army of human soldiers, which means 1 out of 2 orcs hit. If their commander is slain and the orcs roll an 8 on their d12, the orcs that hit are lowered to 1 out of 3.

Siege weapons can be incredibly useful - they can attack enemy army units way sooner than the armies will be able to engage in melee, or even in the range of their ranged attacks. While most siege weapons take a while to load, target and fire, the reward is considerable.
Siege weapons of any size move at 10 feet per combat round. Large siege weapons need 20 medium creatures (or 40 small creatures or 7 large creatures) per siege weapon to be moved and operated. Huge siege weapons need double that amount of creatures to move and operate, and gargantuan siege weapons need four times that amount. Siege weapons cannot move and do anything else - they either move, or prepare to fire.

When Siege Weapons attack an enemy army unit which is engaged in melee combat with another army unit, 3/4 of the damage goes to the enemy army unit and 1/4 of the damage is allocated to the army unit the enemy unit itself is attacking.

An army sheet is helpful if it looks like this:

ARMY UNIT NAME: The race / class of the army unit
Number of Soldiers: The number of soldier the unit had when it was ‘created’. This number is recalculated every time the army unit is merged with another, or divides itself into multiple units (each getting its own sheet)

4/4 HP [100% Effectiveness (x 1 modifier)]: The total number of hp the army unit had at its inception.This number is recalculated every time the army unit is merged with another, or divides itself into multiple units (each getting its own sheet)

3/4 HP [75% Effectiveness (x 0.75 modifier)]: The 3/4 of the number above.

2/4 HP [50% Effectiveness (x 0.5 modifier)]: The 2/4 of the number above.

1/4 HP [25% Effectiveness (x 0.25 modifier)]: The 1/4 of the number above.

0/4 HP [0% Effectiveness (army destroyed)]: 0

HIT POINT BANK: The total damage the army unit has sustained until its turn comes. Once the army unit begins its turn, subtract this number from your current hit points.

CURRENT HIT POINTS: The current hit points the army unit has. When this number reaches a number which is less than 3/4, 2/4, or 1/4 of its hit point total, apply the appropriate multiplier because of lessened effectiveness.

ATTACK ROLL MODIFIER: The attack roll bonus (or penalty) a regular member of the army’s unit has.

ARMOR CLASS: The armor class score a regular member of the army’s unit has.

VIPs: If any VIPs are located in the same space with the army unit, write them down here.

Number of Soldiers: 1000
4/4 HP [100% Effectiveness (x 1 modifier)]: 8000
3/4 HP [75% Effectiveness (x 0.75 modifier)]: 6000
2/4 HP [50% Effectiveness (x 0.5 modifier)]: 4000
1/4 HP [25% Effectiveness (x 0.25 modifier)]: 2000
0/4 HP [0% Effectiveness (army destroyed)]: 0
ATTACK ROLL MODIFIER: +3 (spear, dmg 1d6+1)
VIPs: James Robgill (Male Human Fighter, Lvl 2)
That's it, basically.