D&D 5E Tidbit for monster design

[Sword of Spirit]

Something else I think might help you along this path is that the baseline monster stats by CR in the 2014 DMG don't match values used by WotC. This is a point the designers have brought up a few times over the years, but you can see it pretty clearly in my analysis of published monsters from the 2014 era. This is especially evident when comparing monster attack bonuses and save DCs. As you pointed out, if compare the two, as listed in the 2014 DMG, they imply different underlying stats, which isn't the case when looking at actual monsters.

I still question exactly how it differs. I assume it primarily differs due to most likely doing what I mentioned in the first post--adjusting CR based on actual changes in effective hp and damage from the changed percentages to be hit / hit, rather than using the +2 change = +1 level on the chart. Statistically, that checks out as a simplification of what the actual math does.

I assumed there were other non-simplified versions of calculations, but from the data entry points of that spreadsheet there don't appear to be as many as I hoped there might--although without the calculation portions of the sheet, we can't see what there actually is. For instance, they may still have a calculation for damage resistances that is more granular. And certainly Aggressive must be based on the creature's actual damage output, rather than a flat +2 damage per round (it honestly looks like a straight up mistake in the DMG, but maybe they were just assuming you'd only use it on something with a similar damage output to a basic orc). And it's interesting that there was no line for Save DCs at all, which makes me wonder if there is a separate sheet for monsters that "relies more on effects with saving throws than on attacks" (whatever the criteria for that is).

I don't see any benefit for them to make up different values for the chart in the DMG than the values in the spreadsheet, given the similarities, which makes me believe the differences are in how those values are manipulated, not in what the baseline is. I'd be interested if you have the exact statements for me to review though--maybe they were more clear than I'm assuming.

So far, I've mostly examined the stats in the 2014 MM, in case they made changes afterwards. Actual monsters have higher ACs and Attack Bonuses than the chart gives for the CR. However, this still fits the chart, because they have correspondingly lower hit points and damage output than the chart. So they just set some of the chart assumptions oddly. In the case of AC, it actually makes perfect sense since the chart gives the monster's AC assuming a 65% hit rate, and we can determine exactly what that is for a typical PC using easily established assumptions.

It's much murkier how they came up with the numbers on the Offensive side, though I can at least understand the difficulty, given that the average saving throw of a PC varies only by 2.167 to 2.333 from level 1 to 20. Average PC AC also doesn't vary by many points, though that one is difficult for me to pin down. I assume they wanted the amount of variation over the levels closer to the AC variation in their monster numbers over those levels (though it's odd that the variation in Save DCs is the same 7 points as monster AC, while the variations in Attack Bonuses is 8).

Actual MM Save DCs start a little lower than the ones in the DMG, are the same around 12-15, and then start climbing higher. Actual Attack Bonuses on the other hand, are higher pretty much the whole way, and by a larger amount than the Save DCs.

I'd like to assume those Attack Bonuses and Save DCs workout somehow, given how, as you mentioned, the simplified DMG guidelines do get pretty close results. I'm just not sure where they are getting their numbers. If we ignore the discrepancies between Attack Bonus and Save DC, it doesn't matter too much where they set the numbers, as long as the percentage hit chance multiplied by the given damage number adds up to the amount that deals the appropriate damage to the PCs. They could set it at 95% hit chance, adjusted the damage accordingly, and then we'd just find the actual monsters have much lower Attack Bonuses and higher Damage values than the chart indicates, but it would still work out to the same end result.

Now, some people mistakenly take this to mean the method used in the 2014 DMG is entirely wrong, but, having calculated CRs for over 2,000 monsters using it and seeing how well it holds up, I think a better way of looking at it is as just a different reference point along the same power curve. It's not a good representation of the baseline WotC follows, but you can still use it to calculate monster CRs accurately enough.

When I first started out analyzing official monsters, I stuck pretty close to what WotC described in the DMG. Over time, as I've developed my theoretical model, I've deviated from it more and more. However, despite that, my results still don't differ all that much from what the 2014 DMG gives. I don't think their method for calculating monster CRs is perfect, but I think it does a good enough job to be practically useful in most circumstances.

I'm hoping to test out the formulas I'm coming up with to see if they work where the simplifications in the DMG don't. By limiting my tests to creatures that don't have any of the complications in their statblock to determine what happens, and then add in individual complications, I'm hoping to be able to determine what each does. Unfortunately for this exercise (but fortunately for play experience) there aren't many monsters that have nothing going on but AC, HP, AB, and Damage, which are the values I can test the formulas for. I tried it on all the ones that were limited to values. 14 of those don't get the right CR with the DMG values, and 12 don't get the right values with these formulas. (Including, in both case, the humble ogre. It's really only CR 1, no matter how you do it. I don't know why it's listed as CR 2. It makes me wonder if they initially gave it 2 attacks, and then dropped it to 1 attack without adjusting the CR.)

With there still being 12 (mostly the same ones, though a couple of them were different) extremely simple monsters that don't work, I need to know why they don't work before I can continue. One question I have is if they ever actually ignore what their spreadsheet says and give a monster a different CR than it says. Statements are unclear. I could interpret Mike Mearls as saying that, but I could also interpret him as meaning that if it isn't working quite right, he adjusts the numbers in the spreadsheet until it spits out the CR he wants. And Jeremy Crawford talked about doing exactly the latter with increasing hit points by small amounts.

The thing is, my end goal is actually to adjust the formulas to better fit the assumptions I want to bring to the game. For example, we always play with at least the standard amount of magic items, so I intend to adjust the math to assume the standard magic item allotment. I also find that the DMG vastly overrates the effect of damage resistances and immunities (I stick with the 2014 rules), and intend to change how it handles it to get numbers that make more sense to me (I'm also making more nuanced damage resistances, similar to what 3.5e did, so I'll be adjusting it differently than I would with the standard way of overcoming damage resistances). But before I change the rules, I prefer to understand why they are the way they are as fully as possible.