Dumb question about CR...

[Tura]

OK, this will probably seem terribly stupid, but I have to ask.

The DMG describes how a monster of CR 5 is an appropriate challenge for a party of four 5th level characters. And then, if you want more than one monsters for an encounter, it has a nice table with Number of Creatures corresponding to Encounter Level.

And here's the dumb question. What if the party doesn't have four members, but three, or seven? How do you use the table then???

(Thanks in advance for bearing with me... And if you're feeling particularly kind today, please add a couple of simple examples to make my life easier. Say, for a group of 6 5th level characters, how many 5th lvl humans are appropriate? Or, for a group of 5 2nd lvl characters, how many goblins?)

[Crow]

I add the levels of the party and divide by 4. So three 5's for me would be 3.75 (then I always round up).

For more members (like 7), I add it all up and divide by 4 anyways. So seven 5's for me would be around 7-point-something. When doing it this way, I round down.

[Lord Lorac Silvanos]

I will do you one better. Here is a link to an online encounter calculator where you can make all kinds of party and monster configurations.

However, finding the appropriate EL for a very large or small party can be a bit more difficult and requires a little more thought than just plugging in the numbers, but all that will come with experience.

[Shhalahr Windrider]

Right, mere nunbers will break down quite rapidly. A CR 8 creature does assume characters of around 8th level and all the abilities that level brings with it. Though a party of eight 4th level characters would theoretically be the equivalent of a standard-size 8th level party by the math above*, they will run into problems.

Examples:

• The melee characters have much lower BAB. If the creature has a phenomenal AC for its CR, it will be impossible to hit except on a natural 20.
• If the creature has a nasty ability whose only counter is a 3rd or 4th level spell, the party spellcasters will be unable to deal with that.
• If the creature is capable of dealing a high amount of hp damage, the party won't have sufficient endurance.
• Any ability that is scaled to have worse effects against creatures below a certain HD threshhold is almost guarnteed to have that worse effect against the entire party.
• High save DCs will be next-to-impossible to overcome

And so on.

In short, when going by the numbers, you should use Encounter Level as a guide rather than Challenge Rating, and in doing so you should boos the Encounter Level simply by increasing the number of creatures that a standard size party could face rather than increasing the power level of individual creatures.

[hr]* I'm not certain that math really works out anyway. Consider that an Encounter Level only increases by 2 for each doubling of creatures. Equivalent Party Level should probably scale at the same rate. By the numbers game if a particular number of bad guys is a challenge for a particular number of good guys, scaling each side by the same proportion is what should keep the challenge of each encounter the same.

[goat]

8 level 4 characters up against a CR 6 monster (just the one) will probably rip it apart. The difference in standard actions available makes a massive difference to the flow of the battle. The sheer amounts of battlefield control and de-buffing that the party can apply each round makes their reduced damage output much less significant.

[Kioran]

<hr>* I'm not certain that math really works out anyway. Consider that an Encounter Level only increases by 2 for each doubling of creatures. Equivalent Party Level should probably scale at the same rate. By the numbers game if a particular number of bad guys is a challenge for a particular number of good guys, scaling each side by the same proportion is what should keep the challenge of each encounter the same.

Yes, that´s exactly it - CR +2 = Power*2

So any increase of CR by 1 means an increase of power by approx. 41% (utopic for anything but spellcasters or clever combination of "non-associated classes", but I digress).

So the Logarithm base 1.41 of (Current power divided by 4 Character of that ECL) is the increase in CR.
6 people ar 50% more, so that logarithm is a little over 1 - thats party lvl 6 for your example. Twelve people would 8, and so on). Conversely that means that only 2 Character have an effective party level 2 lower, and three 1 lower.
Please note that this calculation of challenge, while predicting the outcome with some accuracy, almost automatically means that really large groups(more than 6 or 7) will often take casualties in normal combat....

[Triaxx]

When it doubt, even it out. Use a lower CR monster, and add kobold minions. Since a single kobold is a 1/2 CR monster, you can get a fair estimation of the party power.

[Shhalahr Windrider]

8 level 4 characters up against a CR 6 monster (just the one) will probably rip it apart.

Which is why no matter what math you use, the best thing to do is increase the number of creatures of the usual power level rather than simply use the same number of more powerful creatures.

[Kioran]

8 level 4 characters up against a CR 6 monster (just the one) will probably rip it apart. The difference in standard actions available makes a massive difference to the flow of the battle. The sheer amounts of battlefield control and de-buffing that the party can apply each round makes their reduced damage output much less significant.

Very much true, but some monsters (ambushers, or just really fast ones like Air elementals) might get the drop on the group and could rip one character a new one before the others can even act.....so 25% of the ressources sometimes means dead characters.
And talk about CR 8 traps.........

If you use one stronger monster instead of more monsters, the overall challenge doesn´t change too much, the outcome just polarizes more: it´s either easy victory or dead PCs.

[Aquaseafoam]

I take the CR system, then stomp on it a little bit. It's utterly worthless for determining monster strength. Youre better off just taking some monsters, comparing their strengths to your party's, and going from there.

[Chronos]

Which is why no matter what math you use, the best thing to do is increase the number of creatures of the usual power level rather than simply use the same number of more powerful creatures.

With the caveat that some creatures (or characters) have attacks with large areas of effect, or which can otherwise hit large numbers of creatures, in which case they might be just as effective versus larger numbers as versus smaller, and two of them would be twice as effective.

As an example, suppose a single dragon of some type is a fair fight for a party of four. It starts combat with a blast of breath at all four characters, then the party skewers it before it can get a second breath off. With eight characters versus two dragons, though, all eight are going to be hit by two breath weapons at the start, which might be enough to kill them.

[Quietus]

With the caveat that some creatures (or characters) have attacks with large areas of effect, or which can otherwise hit large numbers of creatures, in which case they might be just as effective versus larger numbers as versus smaller, and two of them would be twice as effective.

As an example, suppose a single dragon of some type is a fair fight for a party of four. It starts combat with a blast of breath at all four characters, then the party skewers it before it can get a second breath off. With eight characters versus two dragons, though, all eight are going to be hit by two breath weapons at the start, which might be enough to kill them.

This is where being a DM comes in. The CR system is borked, we know this. As a DM, a person needs to be able to see what their group can handle. In general, for a larger party, send the same CR, but two of them - but dragons are notoriously over-CRed already. I"ve never had a problem with that, since they're, well, DRAGONS, but that's how it goes.

[goat]

And talk about CR 8 traps...

I'm fairly sure the trap CR system is entirely broken. It's possible for a CR 10 trap like this one, to have a disable device DC of 34, and kill you if you fail it.

[Chronos]

but dragons are notoriously over-CRed already. I"ve never had a problem with that, since they're, well, DRAGONS, but that's how it goes.

Note that I specified a situation where the party could handle one dragon, not a dragon with CR matching the party's level.

And yes, they're DRAGONS, but that just means that they should have a higher CR. With things as they are now, the net effect is that newbie DMs can easily TPK a party accidentally, and if players do defeat a dragon, they earn less XP for it than they really deserve.

goat, that trap is indeed insane... A rogue with, say, a 16 Int (pretty good, for a 10th-level rogue) and maxed Search would only have a 15% chance to notice that thing in the first place, and then (with masterwork picks) a 25% chance to disarm it. Things which throw around 9th-level spells should absolutely not be CR 10.

[Lord Tataraus]

Well, this is not exactly what you're looking for, but I personally hardly ever use CR. I just gadge my players' abilities and throw stuff at them that they can take. Of course, this approach requires some experience and a certain amount of comfort with the monsters and such you're using.

[brian c]

I'm fairly sure the trap CR system is entirely broken. It's possible for a CR 10 trap like this one, to have a disable device DC of 34, and kill you if you fail it.

Yeah, but what chance does a lvl 10 Rogue have of setting it off? Remember, you only set off the trap if you fail by 5 or more, so a Rogue needs to get a 30 or better to avoid setting it off. Max ranks = 13, assume about +5 dex modifier gets you to a +18, and magic/items/whatever should get a few more. At about +22, you can succeed on an 8 or higher. If your 10th level ability was skill mastery, you can take 10 and automatically not set it off, with some skill boosting you could auto-succeed.

Yeah, it's a hard trap. But a CR10 monster can kill you too.

[Shhalahr Windrider]

Things which throw around 9th-level spells should absolutely not be CR 10.

Yeah. Problem being that someone decided that traps were too unpredictable to reflect CRs above 10 and so traps have an artificial max CR. As such the most insane traps in the world are CR 10.

Trap includes an epic level spell that destroys the soul but on a successful save only deals 100d10 damage instead? Sure! CR 10!

[deadseashoals]

Technically, you'd calculate the EL of the party and subtract 4 to get the EL of an "average" encounter. So for a party of 4 level 4 PCs, it would be 4, for 5 level 4 PCs, it would be 4~5, 6 would be 5, 7 would be 5~6, and 8 would be 6.

Once you get to 6 or above, however, the numbers don't quite work out the way you'd like. Large parties basically require lots of monsters - a 7v1 will either work out to a massive slaughter as PCs demolish the enemy, who gets 1 action for every 7 they have, or if you make the enemy strong enough to withstand all that, it will likely be capable of killing multiple PCs per action, which is no fun.

[holywhippet]

IMO, it should be more of a matter of ecology than simple math. If you wander into an area where the minotaurs like to frolic, you should expect to run into some. If they are capable of kicking the crap out of the party, the players should be smart enough to run and know not to come back until they have levelled up. If they decide to slug it out then they get to learn the meaning of the words "learning curve".

[Shhalahr Windrider]

Not every encounter is a matter of the PCs wandering into the other monster's territory, you know. Now and then, it's the monster that tracks down the PCs. And from a game perspective it's a bit unfair to say, "Oh the Red Great Wyrm just happened to be out and about hunting in the same area as my 2nd level PCs.

[goat]

Yeah, but what chance does a lvl 10 Rogue have of setting it off? Remember, you only set off the trap if you fail by 5 or more, so a Rogue needs to get a 30 or better to avoid setting it off. Max ranks = 13, assume about +5 dex modifier gets you to a +18, and magic/items/whatever should get a few more. At about +22, you can succeed on an 8 or higher. If your 10th level ability was skill mastery, you can take 10 and automatically not set it off, with some skill boosting you could auto-succeed.

Yeah, it's a hard trap. But a CR10 monster can kill you too.

Oh I agree that it CAN be bypassed, but bypassing it requires finding it. So not only do you need a 34 DD check, you need a 34 search check to even find it. Not many rogues will be carrying items of plus disable device, not all rogues will even max it. Unless you've got a classic dungeoneer, you're going to be struggling.

And if you don't have a rogue or similarly dedicated skill-monkey at all...

[Hyozo]

I take the CR system, then stomp on it a little bit. It's utterly worthless for determining monster strength. Youre better off just taking some monsters, comparing their strengths to your party's, and going from there.

I STRONGLY disagree. Considder older editions, when the amount of experience a monster was worth (and therefore the assumed difficulty of a fight against it) was determined entirely by how many hit dice it had. Consider the first edition Rot Grub, 1 hit point, but when it hit you, unless you "Immediately" burn yourself or have a cure disease spell cast on you, you are dead. It's almost worthless for experience (supposedly making it good for low level parties), but fighting it will kill you, deal 1d6 damage to you, or cost you a spell slot (Remember, "good for low levels"). No matter how you look at it, there was something wrong with the Rot Grub. I'm not saying the CR system is perfect, one of my level one characters faced a pair of Skurrids (only a DM fiat kept it from being a TPK before anybody got to do anything), all I'm saying is that NO edition of D&D has ever had a perfect way to determine how deadly a monster is. Who is to say WotC DIDN'T do just what you suggested? Granted, Swordguy can tell you how stupidly they played the characters, but at least they judge monsters on how able they were to kill a party instead of just how many times you have to stab them before they die.

[Chronos]

Max ranks = 13, assume about +5 dex modifier gets you to a +18, and magic/items/whatever should get a few more. At about +22, you can succeed on an 8 or higher. If your 10th level ability was skill mastery, you can take 10 and automatically not set it off, with some skill boosting you could auto-succeed.

First of all, Disable Device is Int-based, not Dex-based, so figure on a +2 or maybe +3 for the ability modifier, not +5. Second, the only core item which will boost Disable Device is masterwork thieves' tools, which only give +2. There are a couple of spells which would help, if you have them, but not by much (+2 from Fox's Cunning, +2 or +4 from Heroism or Greater Heroism). Third, even granting that you took Disable Device as one of your mastered skills, taking 10 here is just twiddling your thumbs: If you want any chance to get past this trap, you're going to have to roll for it, and risk the 35% chance of triggering it. Really, the only good option the party has for dealing with this thing is a Silence spell, and that's only if they can both discover that it's there and determine what spell it is.

[Tura]

OK, thank you all very much, I think I'll work it out.

[Lord Lorac Silvanos]

OK, thank you all very much, I think I'll work it out.

Yeah sometime you get more than you ask for around here.

Good luck with it.