D&D 5E CR and Encounter Difficulty: Is It Consistently Wrong?

[Pickles JG]

If anyone has a simpler way to prove a relation between CR and XP, by all means show me. Being able to use CR to create balanced encounters would be far simpler than adding and multiplying XP values for several monsters. It's just that I cannot see that link, and thus dissociate the two.

By looking at the table that shows XP value of a given CR?
There is a relationship but it's not given by a formula it's defined.

The other side of the coin is how the power level of PCs grows as CR is described in relation to that (likely to be deadly to a PC of lower level than the CR of a critter). & How many XP a character of a given level needs to progress & how many encounters the design wants you to have at a given level. These all factor in to how many XP a given CR critter will be worth.

I am of the opinion that lower CR creatures are relatively more dangerous than their CR/XP budget would indicate. Possibly their CR is "correct" in that it shows the level at which it is unlikely to be overly deadly but the XP for higher CR monsters is relatively generous compared to the XP value of lower CR critters.

This is the real reason that more monsters are more deadly than their XP budget would indicate. Well half of it - the other bit is that fighting all your day's XP budget at once is obviously more dangerous than fighting it one orc at a time.

 

[FormerlyHemlock]

This is the conclusion I'm drawing from this discussion.

Seems like the sidebar on Challenge Rating (DMG, p. 82) may contain the best advice in the encounter building section: look at monster statistics and abilities, gauge them against your PCs (and players, I'd add), use your judgement. Same as it ever was (prior to 3E, that is).

Actually, let me go a little bit further: encounter difficulty can be eyeballed, and if you're not sure how to eyeball it, it can be telegraphed.

Last week I threw 12 Umber Hulks (93 HP each) and 7 Neogi (46 HP and paralyzing venom, one of them with 8th level spellcasting ability) at 4 3rd level characters... and I didn't feel the least bit guilty about it before I told my PCs in advance what the opposition was likely to be ("between 5 and 15 Neogi, and a similar number of Umber Hulks") and I told my players what Umber Hulk stats are, and they knew they were facing 1500 HP of enemy soldiers complete with siege weaponry.

It turned out that they were smart enough to prevail (maybe with a tiny bit of help from the real-time wall clock, which resulted in my declaring the battle over while it was only 85% won instead of 99%), but they very nearly got killed, and if they had I wouldn't have felt bad about it.

Self-pacing is a thing, and it was a big part of old-school dungeon crawls. You don't get tougher monsters because you personally went up from 5th to 7th level, you get tougher monsters because you are now on level VII of the dungeon! And you can go there whether you are 7th level or 2th or 11th, but the rewards are the same in every case. That way the person doing the eyeballing isn't the DM, it's the players, which is great because they are the ones who will suffer the consequences if they eyeball wrong.

 

[Fanaelialae]

Yeah I can kinda understand that. Although the incentive to divide and conquer is already there even without xp taken into account (it's just easier to win if you split the enemy group into smaller pieces at a time). I think I will experiment with awarding adjusted xp from now on. I prefer a quicker advancement anyway.

That's fair. Low risk / Low reward vs High risk / High reward.

I didn't really think of that since my group tends to obey the following operational guideline:

Low risk / High reward > High risk / High reward > Low risk / Low reward > High risk / Low reward.

If I gave my group that choice they'd always be taking on the largest groups they could find. In fact, they might just try to kite an entire dungeon into one room.

 

[Mistwell]

Encounter difficulty is derived from XP which is derived from CR. Fact.

It's false though. That was just mathematically proven above by Jaelommiss. There is no reliable equation for determining a creature's XP from CR or vice versa, and encounter difficulty CANNOT account for CR in adjustments. If you disagree with him, he just challenged you to come up with it.

A huge portion of the game is building NPCs, modifying monsters, and building new creatures.

Maybe for you, but those are all pretty adjacent rules to the core game rules. There is a reason there is an entire book for those things. It's a much more advanced, wonky proposition to do them, and those rules are not meant to be used to judge encounter difficulty. Indeed they outright say that - new NPCs/Monsters have not been playtested like the official ones, and if you use the optional rules to make your own it might not work quite right the first time and you will have to make adjustments once you see how it works. None of that is a good sign of a set of rules meant to be used to judge encounter difficulty in general.

CR *IS* the primary factor for determining a monsters lethality in the game

Not quite. It's used as a warning light to tell the DM to look closer at the monster relative to the party and see if there is something that would be unusually difficult based on that monster and party, such as immunity to spells below level 6 with a party that only has spells of level 6 or lower. It's not the overall determiner of lethality, just a special kind for that sort of issue. General lethality is determined by the XP budget and encounter difficulty chart - which is purely XP based and does not use CR at all.

and it *IS* directly related to building encounter guidelines.

It's not. If it were, it would be used in them. It's not used in those guidelines, aside from that warning sidebar. There is no reason for you to be using CR for encounter building, unless you're basically looking to strawman the rules and claim they do use CR for it just to then claim the rules are broken because CR doesn't work well for that thing. It's not a helpful argument, for anyone. The rules don't use CR for encounter building, so why dwell on CR's effectiveness in doing something it's not meant to do in the first place?

And I contend the reason for it is mistaken left-over concepts from prior editions that people are not wanting to give up on. That being, CR is not part of encounter building anymore.

 

[FormerlyHemlock]

That's fair. Low risk / Low reward vs High risk / High reward.

I didn't really think of that since my group tends to obey the following operational guideline:

Low risk / High reward > High risk / High reward > Low risk / Low reward > High risk / Low reward.

If I gave my group that choice they'd always be taking on the largest groups they could find. In fact, they might just try to kite an entire dungeon into one room.

N.b. kiting the whole dungeon increases the difficulty (unless you're using AoE spells) without increasing the reward (after the first 15 you're already at maximum 4x multiplier). Fighting 300 hobgoblins in twenty little groups of 15 will give you just as much XP as fighting all 300 at the same time.

 

[Mistwell]

N.b. kiting the whole dungeon increases the difficulty...

This is not a phrase commonly used on this forum. What does it mean?

 

[Fanaelialae]

N.b. kiting the whole dungeon increases the difficulty (unless you're using AoE spells) without increasing the reward (after the first 15 you're already at maximum 4x multiplier). Fighting 300 hobgoblins in twenty little groups of 15 will give you just as much XP as fighting all 300 at the same time.

True!

My dungeons are typically smaller areas with around 2 or 3 dozen monsters. (They're meant to be completed in a single adventuring day or so.)

I suppose if getting xp for difficulty, a group seeking to maximize their XP should ideally aim to fight groups of 15. Of course, if there are less than 30 monsters left in the area, they should try to get them all at once.

 

[Fanaelialae]

This is not a phrase commonly used on this forum. What does it mean?

I believe N.b. stands for Nota bene, and kiting is an MMO term for leading a group of monsters on a chase (often with the intent of gathering them together so your party can kill them quickly with area of effect spells).

 

[eryndel]

As a side note, this world would be in a dark place if we could only rely on functional representations of polynomial order of 2 or less, and to claim a cubic function isn't a "reliable" equation. Frankly, the data looks like a power law might fit better, but that's neither here nor there. The truth is the CR to XP relationship is stepwise discrete. It has a specific value at each discrete level of CR, one that is defined in the Experience Points by Challenge Rating table on page 9 of the Monster Manual. In fact, the text right above their states:

"The number of experience points (XP) a monster is worth is based on its challenge rating."

And then provides the mapping between Challenge Rating and XP which is followed pretty well through all the monsters in that tome. I didn't check all of them, but a cursory glance showed a good match. That table, by the way, is mirrored in the custom creatures section of the DMG.

So you're right, the creating an encounter section is based off of XP, along with multiplicity of creatures and situational effects, but the individual XP value of a monster does have a clear 1:1 relationship to CR, as described in the MM.

The lack of a functional relationship would make it tough to interpolate XP if I wanted to make a creature of CR 2.6, 3.14, or 2i, but as long as I stick with the already defined set of CRs in that table, I know precisely how many XP an individual creature is worth. And, frankly, I can eyeball an XP value if for some reason wanted some unusual CR creature.

As long as I stuck to the real numbers

 

[FormerlyHemlock]

True!

My dungeons are typically smaller areas with around 2 or 3 dozen monsters. (They're meant to be completed in a single adventuring day or so.)

I suppose if getting xp for difficulty, a group seeking to maximize their XP should ideally aim to fight groups of 15. Of course, if there are less than 30 monsters left in the area, they should try to get them all at once.

That's really a problem inherent to the whole "level up by fighting things" system, not to XP multipliers per se. When going by RAW (no multipliers for large groups), the optimal strategy for level-grinding is to fight things one at a time, either by seeking out monsters in dungeons (or random encounters) or, even better, by summoning Allosaurs via Conjure Animals and ordering them to try to kill you, one at a time. Each 3rd level spell slot becomes 450 XP per day. (And yes, summoned creatures do count for XP per MM guidelines.) Even better, tell it to kill your buddy who is 600 feet away and armed with a longbow. Since you can't maximize reward, minimize risk by controlling the scenario.

Granting XP for killing things leads to gamification of the game universe. It leads to PCs viewing dangerous creatures as a resource to be exploited, random encounters as a fun bonus instead of a threat, and crazy thrill-seeking behavior. This isn't necessarily a bad thing, since ultimately it is a game, but it is an oddity.

If you grant extra XP for harder encounters, expect to see certain PCs going into battle blindfolded and naked, fighting with their off-hand, in order to make the fights more "difficult" and thus more efficiently exploit the resource.