This isn't anywhere close to RAW, and it doesn't factor in imposing debilitating conditions at all, making it extremely inaccurate. A monster that deals low damage but can charm, frighten, paralyze, etc. will be much more dangerous than a monster that just deals high damage. I also don't think the difference between a 5 and 10 foot range makes that big a difference, and you forgot to account for bigger creatures within a 15 or 20 foot reach.
75 HP (750), AC 17 (600), immune to fire (40), 24 damage at 5 foot range (24), +2 PB (-500), flight (150), 15 foot cone AOE (-250). I'm not sure how to calculate AOE damage, so I think you missed something here.
Final result: 825.
I don't think this works.
Now I'll try something the system works for, a werewolf.
AC 15 (200), 71 HP (710), skipping Pack tactics because you forgot things like that, 22 damage at 150/600 range (132 ish), proficiency bonus (-500).
75 HP (750), AC 17 (600), immune to fire (40), 24 damage at 5 foot range (24), +2 PB (-500), flight (150), 15 foot cone AOE (-250). I'm not sure how to calculate AOE damage, so I think you missed something here.
Final result: 825.
I don't think this works.
750+600+40+24+Damage at 10ft 48+zero PB bonus+ flying 150+No penalty for AoE range of 15ft -- that totals 1612 which is 512pts more than the MM. It's close.
If you want to know the actual formula that appears to have been used, we can say the following:
damage is roughly sqrt(xp value) * 0.85. Attack bonus is roughly 3 + damage/12. Area damage is counted at double value. Damage is averaged over 3 rounds.
HP is roughly sqrt(xp value)*2.1. AC is roughly 13 + HP/50.
A monster might be higher in one category and lower in another, but evidence for tradeoffs is limited.
Likewise, special attacks (status effects) and special defenses (immunities, legendary resistances, etc) are inconsistently handled and frequently seem to not be counted at all.
This mostly works CR for CR 1/8 (expect 4.5 damage and 10 hp) to 20 (expect 134 damage and 316 hp), monsters above CR 20 seem to fall below the curve (a CR 30, at 155,000 xp, should be 335 damage and 787 hp)
Now I'll try something the system works for, a werewolf.
AC 15 (200), 71 HP (710), skipping Pack tactics because you forgot things like that, 22 damage at 150/600 range (132 ish), proficiency bonus (-500).
Final result: 532.
Still broken, even on simple monsters.
AC15 (200) + 71HP (710) + 22 damage at 120 x6 (132) + 22 damage at 60 x4 (240) + 22 damage at 30 x3 (90) + 22 damage at 10 x2 (44) + (23) and no Area of Effect damage (-250).
My total is 1190.
Why are you calculating damage at every range a monster can reach? I don't think a monster should get bonus points from high range plus bonus points for all the lower ranges it can hit too.
75 HP (750), AC 17 (600), immune to fire (40), 24 damage at 5 foot range (24), +2 PB (-500), flight (150), 15 foot cone AOE (-250). I'm not sure how to calculate AOE damage, so I think you missed something here.
Final result: 825.
I don't think this works.
750+600+40+24+Damage at 10ft 48+zero PB bonus+ flying 150+No penalty for AoE range of 15ft -- that totals 1612 which is 512pts more than the MM. It's close.
No, it's not close. Getting 1,612 is 46% higher than the listed 1,100xp. 46% off is not close in any stretch of the word.
For reference, CR 4 is 1,100 xp whilst 1,612 xp is closer to CR 5 (1,800xp) than it is to CR 4.
This formula simply doesn't work on the face of it, plus it also takes a very bizarre approach of calculating XP and then using that to work back to CR. It's the other way around—CR determines XP.
For anyone wondering the best way to calculate XP, you first need to determine CR which is detailed in the 2014 Dungeon Master's Guide. It's a long and largely heuristic process but can be broken down as follows, assuming you've already made the monster:
Determine the monsters Defensive CR
This is determined by going to this chart and looking up the CR values for your monsters Armor Class and Hit Points. If you have different values for each, you'll want to take the average CR. For example say your monster has AC 17 but 120 hit points. That's CR 10 (at the lowest) and CR 4 respectively. The difference is 6, so halve that and add it to the lower value/subtract from the higher for a defensive CR of 7.
Determine the monsters Offensive CR
Attack bonus and Save DC are fairly easy, just use the one that the monster relies on most for it's damage options
Damage/Round takes a little extra work as you have to do a lot of averages and make some assumptions
Assume all attacks hit and all saves are failed
Assume no critical hits
Assume the monster always uses the most damaging attack options each turn
Assume each damage option deals the average amount of damage
Include the most damaging legendary actions are taken during the round, as well as off-turn damage such as auras
Assume area of effect and other damage effects that can hit multiple creatures hits 2 creatures per use
The best approach is to take the average damage over three hypothetical rounds of combat, which accounts for limited use abilities and spells. For recharge abilities, multiple the average damage (modified by the number of creatures it'll hit) by the probability of recharging. Recharge 5-6 = 1/3 damage and Recharge 6 = 1/6 damage
Going back to the chart, look up the CR of the average damage per round and then average it against the attack bonus or save DC
Apply any special modifiers
Flight increases the monster effective AC—the number you reference on the chart
Various monster features are listed on this chart and how they effect various effective traits
Resistances and immunities adjust effective hit points, as detailed here
Once you have your defensive and offensive CR, average them to get the monsters CR
Now here is the single most important step. Do not skip this step. I cannot repeat this enough, this step is more important than everything above
Okay, glad we've established that. Now for the most important step
Ready for it?
You sure?
Here we go
...
playtest
That's right, playtest. There is no magic formula where you put numbers in and get a balanced monster out. 5th edition simply isn't built that way and anyone who says it is, well, they're lying. Or just wrong. One of the two. Just read this quote from the very section I'm referencing
Creating a monster isn’t just a number-crunching exercise. The guidelines in this chapter can help you create monsters, but the only way to know whether a monster is fun is to playtest it. After seeing your monster in action, you might want to adjust the challenge rating up or down based on your experiences.
Run your monster a few times in some test combats. Get a feel if some of the abilities are deceptively more powerful, or just look powerful on paper. You might have added a spell that isn't fun to use, so you don't, which then brings down the damage output. There are too many variables in the creative space of D&D 5th edition to not playtest.
Once you've done all that and got a CR you feel accurately represents your monster, you look up that CR on this chart: Experience Points by Challenge Rating
It's a long-winded process, I know, but it does give usable results. You will get monsters that are balanced enough to be fun, which is all that matters.
Calculate the monster's XP by adding these figures:
Multiply the HP by 10
if the AC is over14 then add 200 for each point above 14
Count the Immunities and multiply by 40
Count the Resistances and multiply that by 10
Add damage at distance (DaD) 120x6, 60x4, 30x3, 10x2, 5x1
Take the PB, subtract 3, then multiply by 500
If Flying add PBx75
If it delivers AoE damage below 15ft radius subtract 250
If it delivers AoE damage beyond 15ft radius, divide the radius by 5, subtract 3 from the result, then multiply that by 250
Count the number of Legendary Resistances it has and multiply that by 800
Now you have any monster's XP very close to Rules as Written (RaW).
This isn't anywhere close to RAW, and it doesn't factor in imposing debilitating conditions at all, making it extremely inaccurate. A monster that deals low damage but can charm, frighten, paralyze, etc. will be much more dangerous than a monster that just deals high damage. I also don't think the difference between a 5 and 10 foot range makes that big a difference, and you forgot to account for bigger creatures within a 15 or 20 foot reach.
Testing this:
kobold warrior: HP 7 (70), AC 14 (0), DaD is 4 damage at distance 20/60 (16), PB 2 (-500), total xp value -414. Not very close to 25.
Let's test a Red Dragon Wyrmling.
75 HP (750), AC 17 (600), immune to fire (40), 24 damage at 5 foot range (24), +2 PB (-500), flight (150), 15 foot cone AOE (-250). I'm not sure how to calculate AOE damage, so I think you missed something here.
Final result: 825.
I don't think this works.
Now I'll try something the system works for, a werewolf.
AC 15 (200), 71 HP (710), skipping Pack tactics because you forgot things like that, 22 damage at 150/600 range (132 ish), proficiency bonus (-500).
Final result: 532.
Still broken, even on simple monsters.
750+600+40+24+Damage at 10ft 48+zero PB bonus+ flying 150+No penalty for AoE range of 15ft -- that totals 1612 which is 512pts more than the MM. It's close.
AC15 (200) + 71HP (710) + 22 damage at 120 x6 (132) + 22 damage at 60 x4 (240) + 22 damage at 30 x3 (90) + 22 damage at 10 x2 (44) + (23) and no Area of Effect damage (-250).
My total is 1190.
If you want to know the actual formula that appears to have been used, we can say the following:
This mostly works CR for CR 1/8 (expect 4.5 damage and 10 hp) to 20 (expect 134 damage and 316 hp), monsters above CR 20 seem to fall below the curve (a CR 30, at 155,000 xp, should be 335 damage and 787 hp)
Why are you calculating damage at every range a monster can reach? I don't think a monster should get bonus points from high range plus bonus points for all the lower ranges it can hit too.
No, it's not close. Getting 1,612 is 46% higher than the listed 1,100xp. 46% off is not close in any stretch of the word.
For reference, CR 4 is 1,100 xp whilst 1,612 xp is closer to CR 5 (1,800xp) than it is to CR 4.
This formula simply doesn't work on the face of it, plus it also takes a very bizarre approach of calculating XP and then using that to work back to CR. It's the other way around—CR determines XP.
Find my D&D Beyond articles here
For anyone wondering the best way to calculate XP, you first need to determine CR which is detailed in the 2014 Dungeon Master's Guide. It's a long and largely heuristic process but can be broken down as follows, assuming you've already made the monster:
Now here is the single most important step. Do not skip this step. I cannot repeat this enough, this step is more important than everything above
Okay, glad we've established that. Now for the most important step
Ready for it?
You sure?
Here we go
...
playtest
That's right, playtest. There is no magic formula where you put numbers in and get a balanced monster out. 5th edition simply isn't built that way and anyone who says it is, well, they're lying. Or just wrong. One of the two. Just read this quote from the very section I'm referencing
Run your monster a few times in some test combats. Get a feel if some of the abilities are deceptively more powerful, or just look powerful on paper. You might have added a spell that isn't fun to use, so you don't, which then brings down the damage output. There are too many variables in the creative space of D&D 5th edition to not playtest.
Once you've done all that and got a CR you feel accurately represents your monster, you look up that CR on this chart: Experience Points by Challenge Rating
It's a long-winded process, I know, but it does give usable results. You will get monsters that are balanced enough to be fun, which is all that matters.
Find my D&D Beyond articles here