Let's make a mass combat system!

[JimAde]

EDIT (Aug 23): I have dropped this project. Just wanted to state that up front in case somebody starts reading the thread. There are plenty of good ideas from everybody here, though, so read on if you'd like.

Beowolf started this thread asking for a good mass combat system. In his post he referenced this article on 3rdedition.org. The article is by the famous Agimimnon and is basically some ideas toward a mass combat system. As Beowolf points out, it's a GOOD start. Agimimnon challenged his readers to finish the system, but I don't know if anybody took him up on it. How about here? Any interest in fleshing out this interesting idea? I'll post my summary of Agimimnon's ideas below.

EDIT: Here's a link to the rules developed here as they currently stand: Mass Combat Rules

 

[JimAde]

Summary of Agimimnon's ideas

Here's a quick summary of Agimimnon's ideas:

Each unit is all the same type and has HP, AC and Attack Bonus of the individuals, plus a a leadership value (calculated as in the Leadership feat), average damage done and the number of individuals in the unit. So, for example, a unit of 20 Orc Warriors (out of the PHB) would look like this (my guess on the unit leadership modifier):

Unit Name: Orc infantry
Qty: 20
Attack Bonus: +4
Average Damage: 9
AC: 13
HP: 5
Init: 0
Leadership: 8 (10 base, -2 unit discipline)

When a unit attacks, roll:
1d20 + attack bonus + leadership - defender's AC

This gets you a percentage called Attack Efficiency (AE) to use in the next step. For example, if the orcs above are attacking a unit with AC 15 and roll a 10, they get an attack efficiency of

10 + 4 + 8 - 15 = 7%

I assume if your AE is 0 or less the attack has no effect.

You then use the AE to calculate the defender's casualties:

Defender Casualties = (AE * average damage * unit size) / Defenders HP

So to continue the example, if the defending unit has 10 HP, their casualties would be:

(0.07 * 9 * 20) / 10 = 12.6 / 10 = 1.26

Which rounds to one defender taken out of the fight. Whether that defender is killed, injured or captured is not mentioned.

Obviously there is a LOT to do, but I think this is a really good core mechanic.

SO: Opinions? Good basis? Not worth bothering with given the systems that are already out there?

 

[Pyrex]

The AE looks really low. Are you sure you shouldn't be multiplying by 5? (as each increment on a d20 represents 5%)

The leadership bonus also seems huge in comparison to bab, I think it should start at 0 instead of 10 (so the above Orcs have a -2 leadership penalty instead of a +8 bonus)

 

[Beowolf]

Good idea with this thread to compleat agi's system jim!!

Upon my inpection of the rules I thought of what whould happen when a unit had a special attack? for instance ghouls.

I was thinking it would work in a similar way as the rest of the system

(AE + DC of ability) - Defenders appropriate save = those affected or somthing along these lines
the real problem whould be determing the effects of the various abilites
i figured that the number of defenders affected would be the above - those caualties of the ghouls regular attack, effectivly creating more casualties(paralised from the ghouls)

This system still can have many problems from complications
How would we determine the effects of a poison special attack?
Multiple attacks by certain creatures (Ghouls for example)

as you can see a lot has still to be done but i belive over time we can create a quality mass combat system!

 

[JimAde]

The AE looks really low. Are you sure you shouldn't be multiplying by 5? (as each increment on a d20 represents 5%)

The leadership bonus also seems huge in comparison to bab, I think it should start at 0 instead of 10 (so the above Orcs have a -2 leadership penalty instead of a +8 bonus)

Pyrex: I'm pretty sure this is as it was presented. Feel free to check the original article, which is linked in my first post, in case I made a mistake.

I think these numbers are right. Remember that if the damage the unit does is greater than the HP of the defender, each "hit" will actually take out more than one opponent. Say for example these orcs are attacking goblins with 4 HP. Each orc "hit" does 9 points of damage, accounting for more than 2 goblins.

As Agimimnon said in his original article, you can add a flat bonus to all the attack modifiers to make the combat shorter. It will just take play-testing to find the right multiplier/addition (if one is necessary).

I agree with you that the leadership score is a big factor. It is calculated as for the Leadership feat and I assumed a 6th level leader. This is maybe too generous.

Beowolf: Multiple attacks are a big problem. You want it to matter, since it's such an integral part of the regular game. How about this: For attacking, the unit's size counts as its size times # of attacks (so 20 ghouls count as 60 for attacking). Attack modifier and damage would be averaged across all attacks. Ghouls have 2 attacks at +2(1d6+1) and one at +0(1d3). That's +2 for the attack. Total damage is 10.5 points average, divided by 3 is 3.5. Round to 4 I guess. So now the ghoul unit looks like this:

Unit Name: Ghoul Mob
Qty: 20 (60)
Attack Bonus: +2
Average Damage: 4
AC: 14
HP: 13
Init: +2
Leadership: +5 (0 base (no leader), +5 unit discipline)

As another example, here's a unit of veteran swordsmen. They're all 6th level Warriors with Longswords, Weapon Focus and an average of 14 STR. Individually their attacks are +9/+4, 1d8+2

Unit Name: Veteran Infantry
Qty: 20 (40)
Attack Bonus: +7
Average Damage: 7
AC: 15
HP: 33
Init: +2
Leadership: +12 (10 base (8th level leader w/14 CHA), +2 unit discipline)

I like your idea for special attacks (those that get a saving throw) but ghouls are different because the special attack is part of the regular attack. For the ghoul's paralysis, I'd say we have two ways of doing it (off the top of my head):
1) It gets 2 attack rolls. One normal (as modified above) and one like you described. I don't like this as the paralysis shouldn't count as a whole new attack. Most of those paralyzed will be taken out by damage anyway.
2) Just add a number to its damage to reflect the extra casualties for paralysis. It'd be written as 4(+3) to reflect the fact that some people (elves) are immune to it.

 

[Al]

Here's my contribution: area attack spells.

Area Attack Spells can inflict massive damage upon thicked packed ranks of soldiers.

The mechanics are (for casters using normal rules vs. massed opponents)

Damage= (Average Damage x (DC-Average Save)/10 x (BlastRadius/5)).

Thus, a fireball hurled at the above mass of Orc Warriors by a 5th level wizard with Int 16 would read as follows:

Damage= (17.5 x (16-0)/10 x 4) = 112 damage. In other words, the entire platoon just got wiped out

As a full mass combat round action (taking one minute), a unit may assume a 'Loose Formation', which halves damage from area effect spells. However, whilst in Loose Formation, AE is reduced by 4.

 

[Tonguez]

I'm going to share my homebrew Mass Combat System which might give a few more ideas on the way to developing the perfect system so here it is


1. The system uses the stat block for an individual Speed and Initiative for the unit remain unchanged from the individual stat block (eg an Ogre has Spd 40 and Init -1 so does an Ogre Unit). As usual Units should all be the same (mixed units are possible but require more math to determine averages)


2 The basic unit factor is 100. So take the size of your unit and divide by 100
(eg 20 Ogres => Base = 0.2)

3 Unit HP = Ave.HP x Size
so 29 x 20 = 580

4. Unit Rating = base factor x HD x Rank
* Rank Green 1, Regular 2, Hardened 3, Veteran 4, Elite 5

so 20 Ogre Regulars = 0.2 x 4 x 2 = 1.6 => rounded to +1
Unit Rating is added to base creature BAb, AC and Saves

5 Reach Factor = Reach/10 (rounded down) so medium sized creatures have reach 0 whereas Ogres (reach 10) get a Factor of +1 used in rolling attacks

6. Unit Damage is Average Damage of creature x Unit size (Ogre = 12.5 x 20 =>250)


So

Ogre Regulars
Size 20 HP 580
Spd 30 (40) Init -1 UR 1
Bab Melee 9 Reach 1 AC 17
Sv. Fort 7 Rfx 1 Will 2
Damage (Great Club) 250​

7 Rolling Attacks
The Attack Roll is set by rolling (D20 + Unit Bab + Reach factor + Leadership) - Opposed AC
eg Roll 15 + 9 + 1 +0 =>25 - 17(opposed AC) = 8
* Leadership = level of Unit Leader

8 Determining Damage
Penetration% = Attack roll x 5 = > 8x 5 = 40%
Damage from Attack = Unit Damage x Pen%
eg 250 x 40% = 100 (ie the Ogres case 100 pts of damage)
* casualties = Damage/Ave.HP of the creature

9. Morale is a Will check with DC equal to opponents Attack role + leadership + mods eg the above Attack role was 8 so Morale is Will vs DC 8
* mods could be things like differences in UR (eg a UR 3 unit vs a UR 1 unit gets a bonus +2), terrain, special manouveres and battle progress

10 Special Abilities and Spells work as usual

11 Formations
A skirmish/mob unit has UR 0 and is in Loose formation which means they are not sitting ducks vs Area Effect spells
Haven't worked out how other Formations affect rules - things like Face and Flank will need to be determined.

12PC interaction
PCs and Units can interact in two ways either the PC is considered leader of the Unit and uses their own level as the Leadership factor

Another hacknslash option is for the Unit to esentially become stat mods for the PC eg a Barbarian 5 (Bab 5) leading the above Ogre unit would roll their Attack as D20 + BAb + Unit Bab (20 + 5 + 9 = 34). This puts the PCs at the center of the action but might seem silly to some

Third the Unit Ratings can be used as staright opposed roles to determine progress when the battle is just a backdrop to PC actions (ie Ogre Unit UR 1 vs Orc Elite Unit UR 3 => D20 +1 vs D20 +3)

Another example

20 Hardered Medusa
Size 20 HP 660
Spd 30 Init 2 UR 3 (3.6)
Bab 11 Reach 0 AC 18
Sv. Fort 6 Rfx 10 Will 9
Damage (ShortBow) 70 Snakes 50 (+poison 70)​

So Battle Ogres vs Medusa

Roll Init Medusa +3 => 15 Ogres -1 => 12
Medusa Gaze Attack Dc 15 vs Ogres Save d20 + 7 => 25
* actually I'm not sure about targeting of the gaze attack or just leaving it general...

Ogres charge roll Attack
D20 + Unit BAb + Reach + Leadership + Charge mod
11 + 9 +0 +1 +2 => 23 - 18 (Medusa AC) = 5

Penetration = 25% (Attack 5 x 5%)
Damage = 250 x 25% = 62 pts damage (or 3 Medusa down)

Morale DC 5 Medusa get a +2 UR bonus and roll Will save (6 +9+ 2*) vs dc 5
Medusa hold and go to next attack

Medusa unit
Size 17 HP 598
Damage Shortbow 59 Snakes 42 (Poison 59)​

Roll attack Snakes roll 8+11 = 19 - 17 = 2

Penetration => 10% Damage 50x 10% = 4 + Poison Damage 59 X10% = 5
Total damage 9

Ogres Morale check DC 3 (2 + 1(poison)) roll 12+2-2* Ogres Hold
*2 UR difference 1-3 = -2

Ogre Unit
Size 20 HP 571
Damage 250​

 

[JimAde]

Tonguez: Cool! The basic concepts here look similar to Agimimnon's (generate a number based on number, BAB and damage of attacker, subtract defender's AC) but there seems to be a bit more math.
I really like figuring reach into the attack and the morale mechanic looks good. For damage, are you keeping track of the whole unit's HP at all times? That's what it looks like.

Al: great suggestions on attack magic. In your example, why do the Orc Warriors have an average save of 0? Is that their save bonus?

Here's my own shot at doing spells:

Basically, it seems like there are three types of spell we will care about:

1) Terrain spells (Wall of force, etc.)
2) Area Effect Damaging spells
3) Area Effect non-damaging spells

Terrain spells can be run as normal. If the caster has the spell and is not interrupted, it gets cast and you're done.

For damaging spells, we could generate an AE (Attack Efficiency, not Area Effect!) and use the regular system:

Spell AE = (Save DC + Leadership) - (10 + Save Bonus)

There is no attack roll for the spell since in D&D you don't have to roll to cast. We could change this to reflect Concentration checks.
The only other difference is that the spell can't affect more individuals than are in its area of effect. Thus a unit of 100 goblins can't be eliminated with a single fireball, even though it does enough damage.

 

[Magistus71]

Beowolf started this thread asking for a good mass combat system. In his post he referenced this article on 3rdedition.org. The article is by the famous Agimimnon and is basically some ideas toward a mass combat system. As Beowolf points out, it's a GOOD start. Agimimnon challenged his readers to finish the system, but I don't know if anybody took him up on it. How about here? Any interest in fleshing out this interesting idea? I'll post my summary of Agimimnon's ideas below.

There really is no need to do this since Agimimnon's Mass combat really was listing what other Mass Combat rules were doing, such as the rules presented in The Quintessential Fighter book by Mongoose Publishing.

 

[JimAde]

There really is no need to do this since Agimimnon's Mass combat really was listing what other Mass Combat rules were doing, such as the rules presented in The Quintessential Fighter book by Mongoose Publishing.

Ah. I didn't realize that, since I don't have that book. I may continue the exercise anyway, but thanks for the heads-up.