D&D 5E do CRs seem a bit arbitrary?

[Tormyr]

That's not technically correct because you're not accounting for the fact that both, and everyone else, is on the motorway at the same time. That's where poor calibration becomes a problem, you're not just accounting for Bob racing his rice-rocket down main street. You're accounting for the fact that while Bob is doing that, traffic lights are going off randomly, other drivers are on the road, pedestrians are trying to cross and there's the occasional emergency vehicle roaring through.

A single kobold or a single dragon might be well balanced and fitting for its CR against an "ideal" and prepared party. But once you start throwing in bugbears, efreets and lair effects, CR becomes unwieldy because a "challenge" is not a linear, mathematical concept. A single kobold may be a CR 1/4 but 6 kobolds could be a CR2 because the tactics they can employ and effects they can take advantage of increase non-linearly with their numbers.

That's why its important to have a good transportation system, because you'll never know if the guy driving the big-rig is a kobold or a salamander.

The CR 1/4 number for kobolds includes the benefit from pack tactics. Without it (when they are on their own), their CR goes down to CR 1/8.

I would argue that CR is, for the most part, a single, linear, concept. Any anticipated benefits from team tactics that should be easily accessible (such as Pack Tactics) should be included in the CR number. Lair actions should be included in the CR calculation for the boss of the lair. Any unanticipated combinations and benefits from other monsters such as bugbears and efreets should be placed along with terrain advantages as a bump to the overall encounter difficulty.

CR is just a building block. The creative stuff goes in encounter building/balance.

 

[Tony Vargas]

Conversely, a traffic system and roadway built to handle poorly-calibrated, swingy drag racers will have absolutely no problem with careful drivers in Ferraris, but a roadway that assumes everyone is in Ferraris will go down in flames if everyone switches to cheap drag racers.

I know you're off into analogy land, but I think you're fundamentally missing what 'balance' would mean in the context of a CR system - or I'm fundamentally misinterpreting your analogy.

For instance, 3e and 5e both have CR systems. In 3e CR, it's pretty clear that a high-CR monster is going to be tough for a lower-level party to hit - a very high CR will even be tough for to hit for any but the full-BAB members of a same-level party unless they use touch attacks. The reverse is also true: monsters much lower CR than the party will not be useable. So there's a need to keep monster CR relatively close to party level. But, the system's way of building a larger encounter (larger than 1 monster vs the whole party, the default same-level encounter) is to 'break up' that one large monster into two lower-CR ones. Doing this a number of times gets you a large number of too-low CR monsters, and the system fails to deliver a reasonable challenge. The system can also fail to deliver the intended challenge because (as in the title of the thread) the CR can be on the arbitrary side, and a monster can be substantially more or less threatening - even before you take into account how wildly different in ability parties of different compositions or using different strategies can be. So that's a pretty low level of encounter balance.

5e also has a CR system. But, thanks to bounded accuracy, a much higher level monster, while it will still stomp the party horribly, can still miss some of the time, and can still be hit by the party a non-trivial proportion of the time, while, by the same token much lower-CR monsters are still able to hit a higher-level party and inflict a little pain on them, making them meaningful in large enough numbers. The CR system gives the DM and exp budget per day based on party size & level, a rating from easy to deadly based on total exp in a single encounter, /and/ a multiplier based on number of monsters vs number of PC in a single encounter that doesn't affect exp reward or budget but /does/ change the difficulty estimate. That greater complexity of encounter design guidelines gives the DM better tools to deliver something closer to the intended level of difficulty than he had in 3e. Again, that's before the crazy of PC - both class mix and madcap tactics - comes into it. And, again, the CR ratings can be a little on the arbitrary side (even relative to 3e, since bounded accuracy leaves them less to be formulaic with). But, the result is still an improvement in encounter balance.

TLR: that a badly-balanced CR system starts out broken doesn't mean it "doesn't break as easily" as a better-balanced one.

 

[FormerlyHemlock]

The CR 1/4 number for kobolds includes the benefit from pack tactics. Without it (when they are on their own), their CR goes down to CR 1/8.

I would argue that CR is, for the most part, a single, linear, concept. Any anticipated benefits from team tactics that should be easily accessible (such as Pack Tactics) should be included in the CR number. Lair actions should be included in the CR calculation for the boss of the lair. Any unanticipated combinations and benefits from other monsters such as bugbears and efreets should be placed along with terrain advantages as a bump to the overall encounter difficulty.

CR is just a building block. The creative stuff goes in encounter building/balance.

The problem with CR is that it's a linear metric for a sometimes non-linear quantity. Take Banshees for example. Because Banshees are CR 2, the encounter guidelines predict that 2 Banshees will be a Hard challenge for 4 5th level Fighters, but an Easy challenge for 4 8th level fighters. Between 5th and 8th level, fighters pick up +0 to Con saves and no extra attacks. They do pick up some ASIs, but the core dynamics of the Banshee-vs-Fighters fight hardly change: Banshees both get to force a DC 13 Con save to cause instant "death", and a DC 13 Wis save to cause Fear, then they finish you off with a Corrupting Touch for moderate damage. Only that last feature (corrupting touch) gets substantially boosted in 8th level fighters. I'm going to go out on a limb and predict that that the 5th level group will take about as many casualties as the 8th level group against two Banshees, in spite of the fact that CR ratings say the 8th level group should handle twice the XP value of Banshees.

The real difficulty factor for Banshees has very little to do with PC level. It is, "Is the Banshee in sunlight?", because in sunlight her wail doesn't function and she is just a double-strength zombie. It is in this sense that I claim that 5E is robust and CR can be largely ignored: due to Bounded Accuracy, player smarts (research/intel/tactics) tends to dominate the relatively minor bonuses that come from PC level. Banshees are hard when you meet them in the dark, and easy when you meet them in sunlight. No CR needed, unless you are using it as a relatively arbitrary metric for handing out XP gains.

 

[MonsterEnvy]

The problem with CR is that it's a linear metric for a sometimes non-linear quantity. Take Banshees for example. Because Banshees are CR 2, the encounter guidelines predict that 2 Banshees will be a Hard challenge for 4 5th level Fighters, but an Easy challenge for 4 8th level fighters. Between 5th and 8th level, fighters pick up +0 to Con saves and no extra attacks. They do pick up some ASIs, but the core dynamics of the Banshee-vs-Fighters fight hardly change: Banshees both get to force a DC 13 Con save to cause instant "death", and a DC 13 Wis save to cause Fear, then they finish you off with a Corrupting Touch for moderate damage. Only that last feature (corrupting touch) gets substantially boosted in 8th level fighters. I'm going to go out on a limb and predict that that the 5th level group will take about as many casualties as the 8th level group against two Banshees, in spite of the fact that CR ratings say the 8th level group should handle twice the XP value of Banshees.

What kind of fighter has a +0 to Con saves. Also they be able to crush the Banshee's faster even with out extra attacks. Those Ability score increases could have gone to CON or to feats that make crushing the Banshee's even quicker and easier.

 

[FormerlyHemlock]

What kind of fighter has a +0 to Con saves. Also they be able to crush the Banshee's faster even with out extra attacks. Those Ability score increases could have gone to CON or to feats that make crushing the Banshee's even quicker and easier.

"Pick up +0 to Con saves" = "the delta is +0". Proficiency bonus is +3 at 5th level and still +3 at 8th level. Yes, ASIs could have gone to Con, but my observation is that they're relatively unlikely to have done so: Fighter 6 and 8 probably get spent on things like +2 Str, GWM, or Resilient (Wis). Extra offense probably isn't going to make much difference in the Banshee fight, because the Banshees already have enough HP (58) to ensure that they'll get their wails off safely, and +2 to Str isn't going to change that.

Are you just nit-picking, or do you substantively disagree? Do you really think that 8th level fighters can handle twice as much XP worth of Banshees as 5th level fighters can? If so, why?

 

[Tony Vargas]

Do you really think that 8th level fighters can handle twice as much XP worth of Banshees as 5th level fighters can? If so, why?

While it's a good example of how CR might not align perfectly with bounded accuracy, isn't an all-fighter party an aberration? I'd expect encounter guidelines to assume a more mixed party, probably even assume something like the iconic Fighter, Cleric, Magic-user, Thief.

The problem with CR is that it's a linear metric for a sometimes non-linear quantity.

CR is, by itself, sure. But 5e encounter guidelines also include a multiplier based on relative numbers (party outnumbers monsters 5:1 is apparently the base assumption).

 

[Sunseeker]

What kind of fighter has a +0 to Con saves. Also they be able to crush the Banshee's faster even with out extra attacks. Those Ability score increases could have gone to CON or to feats that make crushing the Banshee's even quicker and easier.

A Dex fighter. An archer-fighter. Any of the wondrous fighter build options which don't rely on using your torso as your shield.

 

[Tony Vargas]

A Dex fighter. An archer-fighter. Any of the wondrous fighter build options which don't rely on using your torso as your shield.

I thought the fighter's torso was the wizard's shield? ;P

 

[Sunseeker]

I thought the fighter's torso was the wizard's shield? ;P

Oh right, I forgot that fighter's got a bonus to AC from their face.

 

[Tony Vargas]

Oh right, I forgot that fighter's got a bonus to AC from their face.

It's the big, manly, chin - attacks bounce right off.

(In Hero, there actually was a 'chin block' maneuver...)