I must create a system, or be enslaved by another man's. I will not reason and compare: my business is to create.

- William Blake

Saturday, January 18, 2020

The three-strikes rule for FAST COMBAT - or NPCs, mass combat, etc.

While running Curse of Strahd, I had a problem: the PCs would often ally with NPCs to fight multiple monsters at once.

Now, as a DM, to roll dice for both sides of a conflict feels ridiculous and boring, even more so if some of the NPCs are average-level spell-casters, with spells and actions to choose from. And I can only imagine how tiresome it would be for the players to watch the DM rolling for a fight that doesn't involve them directly.

Of course, you could let your players control the NPCs on their side - which generally I recommend. But, TBH, the players are having a hard time with the number of options they already have, and this wouldn't help.

And I didn't want to handwave it, either. It was important to me if the NPC would survive the battle, and it was interesting to see if they would help the PCs or require help themselves.

Fortunately, there is an easy solution.

I call this the three-strikes rule. Works for lots of things.

In 5e, there are two things that encouraged me to use it.

First, death saving throws - they use a "three strikes" methods already.

Second, how damage and HP work in 5e. For many monsters, an attack deals about one third of a monster's HP in damage (I think I read this here; it isn't exact, but it works). This means that, in average... three hits, and you're out.

So, the solution is pretty simple: when a fight breaks, put the allied NPCs against inimical NPCs with comparable power, and roll a d20. Treat the results similarly to a death saving throw: three failures and the NPC is down, three successes and he is triumphant (and can help the PCs).

[If you want to be fair, a success should happen on 11 or more, but the difference is small]

If an NPC has a few failures but survives, he lost one third of his HP for each failure, and so on.

And if it is really important to save the NPC, well, the PCs can try - when the NPC is down, he starts rolling actual death saving throws.

This is scalable. If a paladin is fighting three goblins (assuming both sides are similar in power), each success means he killed one goblin. You could even use it for mass combat between two forces of similar power level. With a small list of modifiers (+2 for high ground, +4 if your force is twice the size of the other, -2 for each failure you already have, etc.), this is pretty much all you need for huge battles.

It also works for fragile NPCs that do not fight. They probably can not "win", but three failures means they're down. If one NPC is "guarding" another (which happened in my campaign), I might treat the two as a single entity and let the "bodyguard" fall first.

This method has a few advantages:

* You can roll a single die for both sides (success for one side means failure to the other). Inf act, I ask the players to roll for their allies.
* You can abstract all powers, wounds, attacks, etc. in a single roll.

It has a few difficulties, too.

For example, things get a bit complicated if the PCs team up with NPCs against a single powerful NPC. In this case, since you've got only one inimical NPC to manage, you're probably better off defaulting to the original system. And comparing the power of two different sides is not always easy.

But, overall, I find it better than playing each move by the book.

All these elements should be incorporated in the "narrative" of course. This assures the the NPCs power level becomes a bit more explicit. E.g., "when you find the fallen body of your comrade, you notice that there are twenty dead ORCS at his feet", and so on.


  1. Might be fun to complicate it slightly. Add up CR or HD ok each side and roll that many D20s. Match successes (11+) to successes, which cancel out. Any success without a match results in the other side losing a HD from their pool. Treat like a sleep spell, but cumulative, so low HD NPCs die quickly, high HD die last, over several rounds. Keep this separate from any part of the battle the PCs join.

    1. I like it. For 5e, CR is more relevant than HD. My only issue is that it seems like a lot of dice rolling. But I like the idea of adding CR to the mix, letting the redshirts die first.

    2. You can probably scale this up to massed combats well enough that if you feel like it'll be too much rolling per round, make groups.

    3. Yeah, that would be a good idea too.

  2. Good also go the very old school way - Forget hit points and simply treat Hit Dice as "hits" - that's how many hits an NPC can take.

    1. This is a good solution for NPCs too. OTOH, 5e focuses more on damage that "hits". I think CR must be taken into account somehow.


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