Wanted: Simple mass battle rules for summoned creatures (was elementals vs spectres)

[Heathen72]

Hi everyone, It's been a long time with no posts, but I need your thoughts on a gameplay question...

One of my players, a 12th level conjuror/summoner type has developed specialised monster summoning spells to call upon elementals to aid him. It makes him extremely versatile - they can be very effective in combat, and they are very useful out of it too.
Unfortunately, it also means a whole lot more bookkeeping during battles.
For instance, the party were recently attacked by 10 spectres and a death knight, and he held the spectres off with the elementals while the party engaged the death knight.
Now, regardless of whether or not the elementals should be able to fight incorporeal creatures (despite the name of the post, that's not really the issue here) how would you run the combat? I honestly haven't got time to map out the combats of the spectres and the elementals and run a fast paced combat with the death knight. In the end I just made some ad hoc decisions about who (out of the spectres and the elementals) won those combats based on a few dice rolls, but I don't feel overly satisfied.
The player has put a lot of work into developing these spells, so I don't want to arbitrarily ban them (despite elementals being kinda rare in my world, anyway) because we have always played fast and loose with creating new spells, but I do need some way of establishing what the outcome of such combats might be. I mean if a 8 hit die earth elemental fights an 8 hit die wight - who wins? And how many wounds does the victor suffer in the battle?
What are your thoughts? (Or has this already been discussed in a Monster Summoning thread

EDIT: Changed subject heading....

 

[Xeriar]

If creatures on each side are about the same (on their respective sides), you can run a battle with only one creature on each side.

If you want to simulate differences in numbers, square the ratio given.

For example, if their are 3 elementals and 2 spectres, you get a number like 2.25.

Multiply all the damage done by the elemental to the spectre by 2.25.

Then, when its combat is over, you can use the HP remaining to determine how seriously injured everything is..

This is a real simple way to simulate numbers in a fight, anyway.

 

[RangerWickett]

What you can do to adjudicate a complex battle like this is to have simple mass combat rules. This system is only really useful with groups of 4 or more on at least one side.

Determine the effective Encounter Level for each side. This becomes that side's Battle Rating (BR). You'll roll each turn, using the BR as a modifier, to see how much damage each side deals. Since we're calculating the overall effectiveness of a large group, and not just single rolls, we're going to use 3d6 instead of 1d20, since d20 makes it way too easy to have anomalous results. Both have the same average result (10.5).

Each turn of combat, roll 3d6+BR for each side, and consult the following table.

Result - Damage
3 to 6 - The enemy takes no damage.
7 to 10 - The enemy takes 1 damage.
11 to 14 - The enemy takes 2 damage.
15 to 18 - The enemy takes 3 damage.
19+ - The enemy takes 4 damage.
23+ - The enemy takes 5 damage.
27+ - The enemy takes 6 damage.
30+ - The enemy takes 7 damage.
etc.

Roll simultaneously for each side. Damage reduces that side's BR for the next round. When a side's BR is reduce to 0, it is considered obliterated, unable to effectively fight.

If after such a fight you need to determine how tough the survivors are, calculate the ratio of normal healthy BR with current BR, and have each member of the group be reduced to the appropriate percentage of hit points. Calculating spell usage is slightly tougher, but just figure that every round of combat each spellcaster cast a spell.

Example:
8 Spectres (CR 7 each, total EL 13) are fighting three greater earth elementals (CR 9 each, total EL 12). The spectres have BR 13, and the elementals have BR 12.

Round one, roll 3d6+13 for the spectres. The result is 27, so the elementals take 6 damage. Also roll 3d6+12 for the elementals. The result is 21, so the spectres take 4 damage.

Round two. Spectres have BR 9, elementals have BR 6. The results this turn are 15 for the spectres (dealing 3 damage) and 20 for the elementals (dealing 4 damage).

Round three. Spectres have BR 5, elementals have BR 3. The results this turn are 18 for the spectres (dealing 3 damage) and 8 for the elementals (dealing 1 damage).

The elementals are destroyed, and the spectres are reduced to a BR of 4. Compared to their original BR of 13, you can figure that the spectres' powers are down by about 70%. Half might be dead (50%), and the other half might only have 3/5 their full hit points (the other 20%).



The system is rough, and I just came up with it, but it shouldn't be too hard to use.

 

[Heathen72]

Cheers RangerWicket and Xeriar.
I think yours has more potential, RW mainly because it takes into acount the differing Challenge ratings of the opponents, and it seems as though it could be worked out at the start of a combat. It's not quite perfect, but it is quick, which is what I need. Thanks.
Any other ideas, anyone?