In computer games you often fight with your character against tons of monsters running in between of them and tapping "attack button" repeatedly and in few second your kill count is many. But in rpg's usually there is not that many enemies present. Not for the reason heroes couldn't deal with them, but for the simple reason that it would take too much time to handle.
So, I have thought about this to find somekind of conclusion to make an epic battle where hero group fights against (for example) several skeletons without taking that much time in bookkeeping (I have heard that 4th edition has conclusion for this, but I haven't read it, so don't know much about it).
How To Make A Horde Of Enemies?
- Choose monster your players' characters will fight
- Decide how many of them are in fight
- Multiply average hitpoints with how many monsters there are in "horde"
- Add +1 to damage and +1 to hit for every 4th monster
As monsters might be weaker fort the party, calculate Hit Die like this:
- If an individual monster's CR is high enough for party to gain experience points, give experience points normally depending on CR and how many monsters there are. For example ten CR12 monsters are worth of 15.000 exp for 15th level party.
- If an individual monster's CR is too low for party to gain experience points from it, take highest possible level to qualify for experience, multiply it with amount of monsters and divide to 1/4. For example if an individual monsters CR is 3, normally it woulnd't give experience for lvl 12 characters, but you use highest possible level's experience points - 10th level character, 250 experience points - multiply it with amount of monsters and divide by four. So 20 CR3 monsters would be worth of 5000 experience points divided by 4 = 1250 experience points total (to share with a party ofcourse).
Every 4th point damage taken for the horde, decrease 1 from damage and to hit as their volume is decreased. You might want to do a simple chart to cross points where your horde's power stands in, like this:
Skeleton, Medium Sized (D&D 3. Monster Manual)
Hit Dice: 6 HP (no idea about CR, but meh, I use this as 1 because skeleton's got 1HD)
Attacks: 2 claws, +0 melee
Damage: claw 1D4
When horde is at it's full power (121 or more HP) it deals 1D4 + 6 damage and it's to hit is +6. When the horde of skeletons get's weaker, it's attack power decreases.
Horde attacks every character in a combat, unless they are in longe range (rangers with bows, casters etc.) as long as other character's keep horde busy. You might want to roll random die to see, if horde can attack long range heroes that turn. Roll 1D6 with results 1-2 long range combatants are also attacked that turn.
Many of D&D player's enjoy their combat to be mini-game of strategic action moving figures and thinking about their turns as advanced chess. But these rules could come handy if and when you want fast combat against many monsters. Ofcourse you might see, that this doesn't work as well with high CR monsters, as they are great challenge as an individuals. But with these rules, you can take those low CR skeletons out of the closet and put tens of them against your 10+ level party to deal with. And for their effort, they can have also a small amount of experience.