when does CR/EL not work?

[Doug McCrae]

CRs of a few monsters are off. For example the tendriculos from the MM is much too low, but no one ever uses it so it doesn't matter too much. The 3.0 ogre was much more serious as it's a common critter.

All the CR system does is evaluate monsters. Don't expect it to account for party composition, player skill, min-maxing, environment, surprise attacks, luck or a host of other factors. That's something a DM has to do for himself. That doesn't mean the CR system is broken, it means it's doing what it's supposed to do.

The DMG page 50 describes many of the factors which can affect challenge level but doesn't give hard and fast numbers.

 

[WizarDru]

The CR/EL system works, though how well varies from group to group and situation to situation. There are some core issues that need to be recognized, though.

1) As mentioned, the 'core-four' are assumed present, and CRs were computed assuming that certain capacities would be within the PC's grasp. I've long believed that many undead would be CR+1 if a cleric isn't with the party. Ghouls/Ghasts, Bodaks, Devourers and others, for example, feature powers that are potentially TPK without a cleric's protections.

2) When most people review the system, they're really talking about CR and ignoring EL. This is like talking about a car's performance, but without discussing the surface it drives upon. Determining the EL is, regretably, like voodoo sometimes. However, it's necessary. Someone mentioned a wizard with summoning spells above: implicit, I think, in his example was that the wizard HAD ALREADY SUMMONED some monsters as part of an encounter. CR is the same as if you surprised him, perhaps, but the EL is radically different.

3) The CR system depends, implicitly, in the veracity of the numbers assigned to the monsters. And these numbers weren't always correct. The Ogre as a CR2 creature, for example, was off. Further, since 3e wasn't tested nearly as extensively at high-levels as it was for lower ones, CR is less dependable at higher levels. And since monster creation under 3e is primarily a matter of 'compare it with existing monster X...does it seem about as powerful?', there's going to be errors or misjudgements.

4) The CR/EL system is a guideline, not a guarantee....and in a game that uses a pseudo-random number generation technique like dice-rolling, odd things will happen. We call this the 'Everybody Rolls a '1' Eventually' rule. I had an 18th level party destroy a CR23 Winter Wight...because he was arrogant and after literally 20 spells were thrown at him, he rolled a '1' and was destroyed.

5) The ER/CL system under 3e doesn't handle mixed groups or large groups well, for calculation purposes. Computing the EL of an encounter with a mixture of four different CR levels with some having multiple creatures can be difficult to accurately gauge their threat level.


All of which is to say that the CR/EL system under 3e is a pretty darned good tool, when used with the proper mindset. Some folks have worked on improving it for years, now. WotC attempting to supplement it is a laudable goal, and I certainly believe there are lessons to be learned from past work and improved upon.

 

[Mustrum_Ridcully]

Answering to Steel_Winds thread about needing a break from D&D 3.5, I noted a further weakness:

One thing the CR/EL system isn't good at is also gauging the actual challenge of an encounter if either the monsters or the PCs are not at their full power. There are no real guidelines.
A CR = PL encounter is supposed to cost 20 % of the character resources. But what does it mean if the party with these reduced resources ends up in the next combat? If these 20 % contained all the wizards fireball spells, that can change a lot. What if the resources lost where mostly charge from a Wand of Cure Light Wounds?

These are very specific questions. I have no idea if it's actually possible to come up for guidelines for all of them. t might in fact the impossible to use any such guidelines in adventure design, because you have no idea if there is actually a wizard that can cast fireball spells, or if he would use them in a specific encounter. But this might be part of the current game system as a whole, too.

The problem is that the game becomes a bit to unpredictable. Players easily go to the safe side and say "Let's rest, I am not sure we won't need my magic the next time). And you know it's astoundinly easy to die in D&D if you find yourself unprepared (or just rolling a 1 on your best save at the wrong time)...

 

[freyar]

All the CR system does is evaluate monsters. Don't expect it to account for party composition, player skill, min-maxing, environment, surprise attacks, luck or a host of other factors. That's something a DM has to do for himself. That doesn't mean the CR system is broken, it means it's doing what it's supposed to do.

QFT. Party compositions (etc) is one thing that has been complained about ad nauseum that didn't make sense to me.

Hussar, I remember that thread, honest. Just with the number of comments about how terrible CR is, I wondered what situations really cause the breakdown of the CR/EL formulae given in the core books (with appropriate environmental fudging and accounting for party issues). So far, I think we have

• A few specific monsters and maybe more templates.
• Advancing monsters, esp. by HD and certain classes.
• Maybe large numbers of creatures.

Nice comments, everyone, keep them coming.

 

[(Psi)SeveredHead]

QFT. Party compositions (etc) is one thing that has been complained about ad nauseum that didn't make sense to me.

Does it make sense to you now?

Just like characters can be optimized (or not), party composition can be optimized (or not). Not having a healer, for instance, makes things harder. It's not instant death, but a PC taking damage will be in much bigger trouble. Not having a heavy fighter leaves you weak against certain types of monsters. Not having a mage leaves you weak against monsters with obvious weak saving throws and/or lots of weak monsters.

(For instance, a Fireball can take out a chunk of ghasts all at once, which will save the melee fighters much agony. On the same token, a hydra and a troll are two monsters that heal quickly and hit hard; a fighter can try to outfight them, and can win, but with a mage to back them up with save-or-suffer spells they'll do a much better job of killing the monsters.)

 

[Samnell]

Yes, but the problem is with EL/CR as a way to balance encounters vs. the PCs, as a monster which is tough to fight is not necessarily as tough to sneak past or bluff.

Yes, but CR/EL does measure the magnitude of the fight avoided, which is what I'm really giving XP for. If it's a bit harder or easier than open combat, well them's the breaks. I don't begrudge the PCs a little bit of extra XP and they don't begrudge me an encounter that they just couldn't manage the hide rolls to avoid.

 

[freyar]

Does it make sense to you now?

It doesn't make sense to me that the complaints are directed at the CR/EL system. I completely understand about party optimization, though. For example, I worried a lot about whether a 1st level party of a rogue, a dragon shaman, and a beguiler would be able to take on a dread guard (MM2 construct -- CR 3 in 3.5, but I didn't use the extra 20hp from the 3.5 construct rules, so I guessed it would stay CR2). I figured it would be a very tough fight, but I did it anyway. Honestly, I think I evaluated it ok, though the party kind of messed it up by essentially going into the room it was guarding one a a time. Edit: But that's not what CR is supposed to tell you, as has been said above.

 

[Delta]

2) NPC Challenge and 1 on 4 fights.
The CR/EL rules for NPCs with levels don't work out well, even with non-associated class levels for monster. Especially single-classed non-monstrous NPCs often aren't worth their CR. You can't put a Barbarian 14 against a party with average level 10 and expect it to become a tough fight...

And I'll even potentially agree with that. The idea that NPC level = CR is probably unlikely (even thought they do in theory constitute 1/4 of the typical party). Again, what needed to happen was a bunch of playtests of different classes of NPCs against the stock PC party to see how they actually fared; I've never seen reports of anything like that happening.

 

[Ahnehnois]

General - when does CR/EL not work?

IMO, CR/EL never works.

Anytime situational factors affect encounter difficulty, or noncombat encounters play a significant part in the game, or PCs contribute unequally, I think the system fails. Anytime there are different power levels among PCs or enemies, the math gets hard.

I just ad hoc it.

 

[Tinker Gnome]

When making custom monsters, I just eyeball the CR. If it turns out to be too difficult or too easy I adjust the experience accordingly.