Adjusting CR for groups of monsters?

[KrazyHades]

The "official" guide for the CR of a group of monsters is that two monsters of the same CR have a total CR of that plus 2. For example, two CR 4 monsters should have a CR 6 together.

However, as I am sure many of you are aware, this rule really doesn't work at all. Two human level four clerics have no chance of challenging a level 6 party, even if they buff themselves. Chances are, they won't live long enough to have more than one or two turns.

This failure in the rules has really bothered me lately, as the latest adventure I wrote was (largely) a cakewalk, with the PCs not even taking damage until the last two encounters (of course, a PC almost died facing down the numblewright, but that's another story).

What is a good rule to help judge the ACTUAL challenge rating of an encounter involving multiple enemies?

 

[MithrasRahl]

You're missing a key part to that system though, which is how the Encounter Level compares to the Party Level, and what the difference means.

A group of 4 ECL 6 PCs means a party level of 6. 2 CR 4s is an encounter level of 6, which is deemed "Challenging", aka supposed to be 50% of the encounters the party faces. According to the DMG, "the average party should be able to handle 4 challenging encounters before running low on hit points, spells, etc."

My suggestion would be to either have them face more of the above situations in a given day, so that there is no time to rest up, or to up the challenge to Very Difficult.

To go back to your example, maybe on the first round the 2 cleric would Hold Person on the Fighters, and then both Inflict Moderate Wounds on the Wizard in the second round, doing an average of 13 DMG each to a wizard that would have from 19-27 health.

So now you have a potentially unconscious wizard, 2 fighters that are Held, and the final PC. The Clerics from there can cast things like Spiritual Weapon, Summon Monster II, etc.

The DMG calls for an array of difficulties, from easy to overpowering, and it is up to you to decide which your party has more fun fighting, and go from there.

For example, 2 CR 5 or CR 6 monsters/bad guys would be an Encounter level of 7 or 8, which rates as "Very Difficult" when compared to the Party level of 6.

...sorry if this post is kinda rambly and all over the place, I added in thoughts and Im also really tired

 

[Shin Okada]

First of all, there is no such thing as "the CR of a group of monsters". CR is for one monster. What you are saying is EL (encounter level).

And yes, two L4 clerics are EL 6 encounter. They are expected to let a 6th-level party spend some amount of resources (HP, spells, etc.), but are not expected to seriously injure the party. And in my experience, this calculation usually works. At least, that duo are as effective opponent as a single 6th-level NPC cleric.

Basically, if played popery, a bunch of slightly weaker opponent has more chance to harm PCs than a single big opponent has. Especially when they are spell casters.

 

[eamon]

I find the addition rules work fairly well.

However, and especially (if like me) you let you players run a little high on the power curve (28 or 32 point buy, at least reasonably optimized), an EL6 encounter is no challenge to a 6th level party. At best, it'll consume some resources, but if you don't have that many battles in a day, that just won't make a difference.

In my experience you'll need to go to at least EL of party level +4 for a serious challenge if that's the only thing you do in a day. If you run a little lower power campaign, it might be only +3 or even +2, and if you really play high-power then it'll be a bit more.

But in any case, that's the beauty of it all, it's pretty easy to scale. Apparently, EL of party level isn't difficult enough for your playing style, so you can let them do more difficult tasks...

In general, though not quite so at low-ish levels (6th is somewhere in between), multiple weak monsters work better in that they're more challenging but also less risky (less "whoops lost initiative and we're already a player down!")