D&D 5E Monster Math: CR1 vs CR½ - Quantifying the differences

[surfarcher]

Monster Math: CR1 vs CR½ - Quantifying the differences

So for the next article in my analysis series I am working on a CR evaluation method. It's a pretty flexible model and aims to produce results in the neighbourhood of +/-5% of traditional deeper monster analysis and evaluation methods.

Why not just use DPR? Well that method is fairly complicated and most DMs simply won't be able to use it. And frankly I believe it's not entirely necessary in 5e.

Now, I'm in the right ballpark for accuracy with the CR1+ monsters in my sample set and getting excellent results. There does seem to be some overlap between adjacent CRs in 5e, but it's something the model copes with without any problems... at least from CR1 onwards.

But with monsters of CR1 and below the overlap becomes more pronounced. The monsters at the lower end of CR1 overlap those at the top end of CR½ more than I would like. And then there's similar overlap between CR½ and ¼ and so forth down to CR0.

Some of the CR1 monsters involved...

• Animated Armor (CR1, 33hp, AC18, +4 to-hit, 11 NAD). (No longer overlaps CR½)
• Dragonclaw (CR1, 16hp, AC14, +5 to-hit, 16.5 NAD). (No longer overlaps CR½)
• Fire Snake (CR1, 22hp, AC14, +3 to-hit, 21 NAD). (No longer overlaps CR½)
• Imp (CR1, 10hp, AC13, +5 to-hit, 13.38 NAD).
• Lion (CR1, 26hp, AC12, +5 to-hit, 10.75 NAD).
• Quasit (CR1, 7hp, AC13, +4 to-hit, 13.13 NAD).

And some of the CR½ monsters...

• Ape (CR½, 19hp, AC12, +5 to-hit, 13 NAD).
• Black Bear (CR½, 19hp, AC11, +3 to-hit, 12.5 NAD).
• Gray Ooze (CR½, 22hp, AC8, +3 to-hit, 11.5 NAD).
• Lizardfolk (CR½, 22hp, AC15, +4 to-hit, 11.0 NAD).
• Satyr (CR½, 31hp, AC14, +5 to-hit, 6.5 NAD).
• Scout (CR½, 16hp, AC13, +4 to-hit, 11 NAD). (Added)
• Thug (CR½, 32hp, AC11, +4 to-hit, 11 NAD).
• Worg (CR½, 26hp, AC13, +5 to-hit, 10 NAD).

The above are, of course, for very high-level comparison only. Proper evaluation requires consideration of the rest of the monster including other defences, how the monster is run, etc, etc.

Notes...

• NAD is "Notional Average Damage". A monster with Multiattack that uses two 5 average damage melee attacks would have a 10 here. A monster that normally attacks with an average 5 damage attack but has a recharge 5-6 attack that does an average 13 damage has a NAD of 7.666. (5 * (2/3)) + (13 * (1/3)) = 3.333 + 4.333 = 7.666
• While NAD is used by the evaluation process it's only a variable in that process.
• The other stats listed are also variables in the assessment process.
• There are other variables and constants in the assessment process not listed here.

I have no doubt that at least some of the overlap is due to my own mis-evaluation. For example some feel strongly that the Lion gets to use Pounce more than 50% and they may well be right.

So I am opening the door to community comment on how you quantitatively (or at least compellingly) differentiate creatures as being in CR1, rather than in CR½. And vice versa.

While opinions are fine things and folks are entitled to them they really aren't going to be of much use in this discussion, unless you can clearly support them. Subjective value statements like "the Thug is not CR1 because it clearly isn't a threat to a CR1 party" are no help. Compelling and/or measurable reasons are most useful. "2 Thugs were no challenge to my PCs" isn't measurable but "The Thug's damage is lower than indicated because of X" is. "The Lion is more of a threat than the Thug" isn't specific or compelling, but "The Lion uses Pounce on average 80% or the time, not 50% the time, because of X" is.

So if we could try to focus on measurable and/or compelling differentiators that would be greatly appreciated.

Thanks in advance for all honest discussion and contributions!

Edit record: All edits noted in green italic above...
29-Oct-14: Corrected NAD for almost all monsters. Several CR1 monsters no longer overlap with CR½. Added the Scout.

 

[ccooke]

A few things:

1) The Scout NPC is at least as dangerous as the Thug. Half the hit points, but AC13 and either two shortsword attacks (which using your NAD formula would get 11 damage) or two longbow attacks (13). They have a decent Stealth bonus and advantage on Wisdom[Perception] - in any circumstance they're going to be used, they are good at hitting from ambush, good at peppering the PCs with ranged attacks while staying under cover and good at getting away to summon help if things go badly.

2) forget comparing the Thug to the Lion. Compare Lions and Worgs.

They both have 26hp. they both get +5 to attack. The worg does 2d6+3 damage, with a chance to knock prone. It has an AC of 13, 1 point more than the lion.
The lion, however, gets pack tactics, pounce and leap.

the druid in one of my games has been shifting into a lion in the last few games. She's getting to use Pounce about one round in three, but always picks something to pounce on that has an ally adjacent to it - which means the Pounce claw attack is with advantage. However, she's getting the extra attack from Pounce more often than you would think, because the extra bit attack happens any time the target is prone - even if it's been knocked prone by someone else. Such as the other lions she's concentrating on Conjure Animals for. Three or more lions are a serious threat, since they have a very good chance of taking people down then attacking with advantage. Extra attacks happen on somewhere between 50% and 70% of Pounces, if there's more than one lion or other creature that can knock people prone around.

Conclusion: The lion is a much greater offensive threat than the Worg.

3) Compare the Thug to the Worg. I've used both recently (a pack of thugs who were raising worgs, in fact).
They're both CR1/2. The Worg has AC 13 and does a lot of damage on its single hit. The Thug attacks twice, often with Pack Tactics. It's noticeably easier to hit, though, with an AC of 11.

They play differently, but at about the same threat level - the Worg is self-sufficient, since it has a slightly higher AC and can knock people prone. The Thug needs an ally to work well, but is able to match the Worg's damage output and might survive for one or two more hits than a Worg.

In terms of numbers, I used five Thugs and three Worgs. The Worgs were mobile, running in to attack the first wave of the PCs. With a DC13 strength save to knock prone, they went for weaker party members while the thugs ran in and engaged the front-line fighters. With the granted advantage, the Thugs were a reasonable force - however, almost every attack hit on them and they did go down quickly. As soon as there was only one Thug left, its damage output dropped by about a third. One of the Worgs was trapped by good player strategy, but the other two outlived all the thugs. Targetting the non-front-line fighters, they were able to knock their targets prone around half the time, which meant they could attack with advantage next turn. Notably the two that survived attacked together. the 50% of the time when the first attack knocked their target prone, the second Worg's attack had advantage.

Less precise there, since I don't recall enough exact numbers. In terms of feel, Worgs and Thugs definitely "feel" about right for power levels.

 

[pemerton]

Some of the CR1 monsters involved...

• Animated Armor (CR1, 33hp, AC18, +4 to-hit, 5 NAD).

In the Rise of Tiamat PDF this monster has 2 attacks, so 10 NAD.

 

[ccooke]

In the Rise of Tiamat PDF this monster has 2 attacks, so 10 NAD.

Also in the Monster Manual

 

[surfarcher]

Also in the Monster Manual

Also in Basic DM v0.1, which is where I got it from. Damned fat fingers! I will correct this in post #1! Thank you peoples!

 

[surfarcher]

A few things:

1) The Scout NPC is at least as dangerous as the Thug. Half the hit points, but AC13 and either two shortsword attacks (which using your NAD formula would get 11 damage) or two longbow attacks (13). They have a decent Stealth bonus and advantage on Wisdom[Perception] - in any circumstance they're going to be used, they are good at hitting from ambush, good at peppering the PCs with ranged attacks while staying under cover and good at getting away to summon help if things go badly.

OK good. I'll add the Scout shortly. The high Stealth/Perception suggests they are designed for ambush attacks and if they focus-fire a single PC in the surprise round (and most of the PCs will likely be surprised) they could easily 0 or kill one PC outright.

2) forget comparing the Thug to the Lion. Compare Lions and Worgs.

They both have 26hp. they both get +5 to attack. The worg does 2d6+3 damage, with a chance to knock prone. It has an AC of 13, 1 point more than the lion.
The lion, however, gets pack tactics, pounce and leap.

the druid in one of my games has been shifting into a lion in the last few games. She's getting to use Pounce about one round in three, but always picks something to pounce on that has an ally adjacent to it - which means the Pounce claw attack is with advantage. However, she's getting the extra attack from Pounce more often than you would think, because the extra bit attack happens any time the target is prone - even if it's been knocked prone by someone else. Such as the other lions she's concentrating on Conjure Animals for. Three or more lions are a serious threat, since they have a very good chance of taking people down then attacking with advantage. Extra attacks happen on somewhere between 50% and 70% of Pounces, if there's more than one lion or other creature that can knock people prone around.

Conclusion: The lion is a much greater offensive threat than the Worg.

Ah! So there's a synergy with the prone part that offsets the save to be knocked prone. So two Lions are far more dangerous than one Lion and an identical CR1 allied creature that cannot knock prone. % of attacks with Advantage (and % of defence with Advantage) may be important factors I haven't included.

The Lion is also an ambusher and on it's may own have a significant chance of 0-ing or killing a single PC in round 1 due to surprise.

3) Compare the Thug to the Worg. I've used both recently (a pack of thugs who were raising worgs, in fact).
They're both CR1/2. The Worg has AC 13 and does a lot of damage on its single hit. The Thug attacks twice, often with Pack Tactics. It's noticeably easier to hit, though, with an AC of 11.

They play differently, but at about the same threat level - the Worg is self-sufficient, since it has a slightly higher AC and can knock people prone. The Thug needs an ally to work well, but is able to match the Worg's damage output and might survive for one or two more hits than a Worg.

In terms of numbers, I used five Thugs and three Worgs. The Worgs were mobile, running in to attack the first wave of the PCs. With a DC13 strength save to knock prone, they went for weaker party members while the thugs ran in and engaged the front-line fighters. With the granted advantage, the Thugs were a reasonable force - however, almost every attack hit on them and they did go down quickly. As soon as there was only one Thug left, its damage output dropped by about a third. One of the Worgs was trapped by good player strategy, but the other two outlived all the thugs. Targeting the non-front-line fighters, they were able to knock their targets prone around half the time, which meant they could attack with advantage next turn. Notably the two that survived attacked together. the 50% of the time when the first attack knocked their target prone, the second Worg's attack had advantage.

Less precise there, since I don't recall enough exact numbers. In terms of feel, Worgs and Thugs definitely "feel" about right for power levels.

Definitely interesting and in the spirit of the thread, so thank you for sharing that! I'm interested to hear what others think of this too.

 

[surfarcher]

OK I noticed I'd copy-pasted some of the NADs from the various sources instead of actually calculating them. I'll update post #1 now.

Between that, factoring in advantage/disadvantage percent and separating out things like resistance much of CR1 vs CR½ has clarified.

But no matter how I turn them and try to look at them differently I just can't see these two guys as CR1...

• Imp
• Quasit

Thoughts?

 

[ccooke]

The Imp has very few hit points, yes. However, it has a number of advantages.
Firstly, it resists bludgeoning, piercing and slashing from nonmagical weapons that aren't silvered. That will effectively double its hit points in melee.
Secondly, it has advantage on saves against spells and magic and is immune to fire and poison. Since that helps to cut out a lot of magical attacks, it will increase its longevity.
Thirdly, it has a powerful attack with extra poison and it can turn invisible with an action.

Tactics for the Imp: Use its invisibility and good Stealth bonus to ambush the party. During the surprise round, attack someone. In the first round after, become invisible. During the second round after surprise, attack someone with advantage while invisible. Third round, invisible and move out of range. Lather, rinse, repeat.
That's going to be a scary fight with one imp against a level 1 party - it could very easily drop someone every time it attacks, if they fail their save against the poison. Even if they save, since it's 3d6 with half damage on a successful save.
With a higher level party, you have more imps - with one or more coming out of invisibility to attack every round while others blink out. Again, not pleasant at all.

 

[ccooke]

The quasit: Fewer hit points than the imp. Isn't immune to fire. However, it has more resistances: In addition to everything the Imp resists, it also resists silvered weapons, cold, fire and lightning. Which means it's effectively at 14 hit points to most of the attacks the party has, especially at low level.
Its attack does less damage, the extra poison effect is slightly easier to resist and does less damage. However, it applies the poisoned condition for up to a minute, which imposes disadvantage on attacks and ability checks.
It has the same ability to turn invisible and the same stealth bonus as the Imp, so similar tactics to the imp are possible. In addition, each quasit can use Scare once per day to potentially impose the Frightened condition on a target, which is a pretty powerful debuff.

 

[ccooke]

Basically, the Imp and quasit look weak, but they have a lot of abilities that can cause havoc in a party. There's nothing like them among the CR½ creatures

I'd draw this general rule out:

CR1 creatures often have the same basic combat statistics as CR½ creatures, but those that do will have situational abilities that make them tactically a much greater threat. Being situational, those abilities will not help them in every situation, but where they apply the threat level is much greater than a similar CR½ creature could provide. Every CR1 creature I've looked at has one (and not usually more than one) of:

• Better survivability than a CR½ creature
• Better pure mathematical offensive ability than a CR½ creature
• A much higher threat level when used in ambush than a CR½ creature
• A much higher threat level when paired with similar allies than a CR½ creature