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D&D 5E Ridiculously Simple Monster Building

NotAYakk

Legend
People complain that the DMG CR stuff doesn't work. And it really doesn't work for the use most people put it to.

So here is a system based off the DMG CR stuff, but upside down. Instead of starting with stats and generating CR, this starts with CR and gives you a budget to buy stats. The result should be within a few percent of doing it the other way.

Warning: I made no attempt to make this work for sub-1 CR monsters. There is probably a budget we can use for them, I just didn't work it out (yet).

---
Simple Monster Building

Start with a CR. Your CR determines your proficiency bonus and your MBP (monster building point) budget.

You get 14 MBP "base" plus 4 MBP for every CR up to 20, and 12 for every CR beyond 19. (CR 20+ monsters get 3xs of HP and damage per additional CR in DMG chart)

You also get 1 bonus MBP at CR 5, 11, and 17 (because I needed a few more MBP at 20 to make the math work, and doing it at the tier barriers makes sense).

Now work out the monster's stats.

For Free you get:
0 standard attack
10 AC
10(+0) in your attack stat (spellcasting stat, or weapon)
0 HP

A base template, to start with something halfway usable, might be:
12 standard attack damage (4)
13 AC (3)
16 in your attack stat (3)
32 HP (4)
This costs you your 14 "free" MBP.

To calculate your attack bonus/save DCs, use your attack stat plus your proficiency bonus.

Note that your attack stat, if it adds to damage, must be paid for in the damage calculation.

Now you spend your MBPs:

Things to buy:
8 HP for each 1 MBP
+/- 1 AC for +/- 1 MBP (can even sell AC! But don't go crazy.)
+3 standard attack routine damage for 1 MBP
+3 legendary action/off turn/bonus attack damage for 1 MBP (total damage; 3 legendary actions doing 10 each is 30/3 = 10 MBP)
+2 primary attack/save DC attribute (a +1 attribute modifier) for 1 MBP (or -2 to get 1 back). (if you have more than one, average them. If one is used way more than the other, ignore the other one).
9 points of single-use damage for 1 MBP. If this replaces your standard attack attack routine, only pay for the damage difference.
A save proficiency is 1 MBP.
Legendary resists cost 2 MBP for the first, then 1 for each one afterwards (up to 3).
Significant resistances/immunities doubles the cost of buying HP (or more or less)
Significant vulnerabilities halves HP cost
Flying at or under 9 CR is worth 2 MBP

Attacks that are area effects (1/2 damage on save) should be assumed to hit more than 1 target; multiply their effective damage before calculating their cost.

Various other abilities have costs. You can wing it, or you can look them up in the monster building rules in the DMG and translate it to AC/ATK (at 1 MBP per AC/ATK).

---

I'm going to make a CR 5 moon griffon. I get 35 points (14 + 5*4, plus 1 bonus for CR 5).

I start with a Griffon

It gets 18 strength (4 MBP)
It flies (2 MBP)
It has 12 AC (2 MBP)
Its attacks deal 1d8+4 radiant damage (beak) and 2d6+4 radiant damage (claws) (19.5) (6.5 MBP)
It has 59 HP (7.4 MBP)
(note: 21.9 MBP; a CR 2 monster gets 22, so the Griffon is CR 2, as expected)

Then I boost it:
It is invisible unless in sunlight (4 MBP for advantage on both attacks and defenses; I assume it doesn't engage in sunlight. PCs with sunlight powers are rare at level 5ish)
It is resistant to weapon damage and immune to radiant damage (7.4 MBP from double HP cost)
Radiant Aura: creatures who on their turn approach within 5' or end their turn there, take 1d10 radiant damage (con save 16 DC for half) 3.7 MBP, discounted by 2 MBP because its effective use is exclusive with flying (1.7 MBP))

Total spent: 35 MBP

There we go, a moon griffon.

Math:
So we start by noting that each +15 HP and +6 damage ups your offensive/defensive CR by 1.

Each +2 AC and +2 ATK ups your offensive or defensive CR by 2. And CR is the average of offensive and defensive; so +4 AC or +4 ATK is worth 1 CR.

I'll invert this, and make each CR be worth 4 monster building points, which you then can buy ATK and AC with.

We now just need to get CR 19 and CR 1 to line up; the middle does a pretty good job on its own.

CR 1 is 78 HP, 13 AC, 11.5 damage, and +1 ATK over proficiency.
CR 19 is 348 HP, 19 AC, 119.5 damage, and +4 ATK over proficiency.

That is +270 HP, +6 AC, 108 damage and +3 ATK for 79 MBP.

We subtract out the AC and ATK (already set at 1 each) giving us 70 MBP to buy 270 HP and 108 damage.

Now, the chart has 6 damage for 1 offensive CR. 3 is half that. Lets do 108/3 is 36 MBP worth of damage, leaving 34 MBP to buy 270 HP.

270/34 is 7.9. Call it 8 HP per MBP.

Next we start with the CR 1 monster.

78/8 is 9.75 MBP for HP
11.5 damage is is 3.8 MBP for damage
10+3 AC is 3 MBP
+3 ATK is 1 above proficiency, for 1 MBP.
Total is 17.55. We need to shave this down so you can afford CR 1 with 4 MBP.

We round this to 18 MBP, giving us 14 MBP + 4 per CR.

The sample is just aimed giving a reasonable starting set of stats.
16 strength, 12 damage, 32 HP, 13 AC.

Note that when doing this review of the math, I noticed an error; the original price of HP was 7 per MBP, and I adjusted it to 8 after I spotted my error.

Some simple templates. You can start with a CR X bruiser, and add stuff to it out of the above budgets.

CR 2 bruiser. 22 MBP budget
AC 15 (5 MBP)
52 HP (6.5 MBP)
+4 attack stat (4 MBP)
2 attacks, each for 1d10+4 (19 DPR) (6.3 MBP)
Total. 21.8 MBP

CR 5 bruiser. 35 MBP budget.
AC 18 (8 MBP)
+5 attack stat (5 MBP)
100 HP (12.5 MBP)
2 attacks, each for 2d8+5 (28 DPR) (9.3 MBP)
Total: 34.8 MBP

CR 11 bruiser. 60 MBP budget.
AC 20 (10 MBP)
+6 attack stat (6 MBP)
150 HP (18.8 MBP)
2 good saves (2 MBP)
3 attacks, each for 3d6+6 (49.5 DPR) (16.5 MBP)
special attack (10d6, large aoe, DC 18) (105 Damage-49.5) (6.2 MBP)
Total: 59.5 MBP

CR 17 bruiser. 85 MBP budget.
AC 21 (11 MBP)
+8 attack stat (8 MBP)
230 HP (28.8 MBP)
4 good saves (4 MBP)
3 attacks, each for 2d12+8 (63 DPR) (21 MBP)
special attack (10d10, large aoe, 21 DC)(165 damage-63) (11.3 MBP)
Total: 84.1 MBP spent

CR 20 bruiser. 105 MBP budget
AC 23 (13 MBP)
+9 attack stat (9 MBP)
250 HP (31.3 MBP)
4 good saves (4 MBP)
3 attacks, each for 3d12+9 (85.5 DPR) (28.5 MBP)
special attack (bonus action, large aoe, 23 DC) 10d10 (165 dam) (18.3 MBP)

Total: 104.1 MBP spent

CR 25 bruiser. 165 MBP budget
AC 25 (15 MBP)
+10 attack stat (10 MBP)
400 HP (50 MBP)
5 good saves (5 MBP)
3 legendary resists (4 MBP)
Magic resistance (2 MBP)
3 attacks each for 3d12+10 (88.5 DPR) (29.5 MBP)
3 legendary actions each for 3d12+10 (88.5 DPR) (29.5 MBP)
special attack (bonus action, large aoe, 23 DC) 10d12 (195 dam) (21.7 MBP)

Total: 166.7 MBP spent
 
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Oofta

Title? I don't need no stinkin' title.
People complain that the DMG CR stuff doesn't work. And it really doesn't work for the use most people put it to.

So here is a system based off the DMG CR stuff, but upside down. Instead of starting with stats and generating CR, this starts with CR and gives you a budget to buy stats. The result should be within a few percent of doing it the other way.

Warning: I made no attempt to make this work for sub-1 CR monsters. There is probably a budget we can use for them, I just didn't work it out (yet).

---
Simple Monster Building

Start with a CR. Your CR determines your proficiency bonus and your MBP (monster building point) budget.

You get 4 MBP for every CR up to 20, and 12 for every CR beyond 20.

You also get 1 bonus MBP at CR 5, 11 and 17 (because I needed 3 more MBP at 20 to make the math work, and doing it at the tier barriers makes sense).

Now work out the monster's stats.

For Free you get:
12 standard attack routine damage (4 MBP worth)
14 AC
16 in your attack stat (spellcasting stat, or weapon)
28 HP (4 MBP worth)

To calculate your attack bonus/save DCs, use your attack stat plus your proficiency bonus.

Note that your attack stat, if it adds to damage, must be paid for in the damage calculation.

Now you spend your MBPs:

Things to buy:
+/- 7 HP for +/- 1 MBP
+/- 1 AC for +/- 1 MBP (can even sell AC! But don't go crazy.)
+3 standard attack routine damage for 1 MBP
+3 legendary action/off turn/bonus attack damage for 1 MBP
+2 attack attribute for 1 MBP (or -2 to get 1 back). (if you have more than one, use a weighted average of them based on how much 3 round damage budget each is used for)
9 points of single-use damage for 1 MBP. If this replaces your standard attack attack routine, only pay for the damage difference.
A save proficiency is 1 MBP.
Legendary resists cost 2 MBP for the first, then 1 for each one afterwards (up to 3).
Significant resistances/immunities costs 4 MBP, and doubles cost of buying HP (or more or less)
Significant vulnerabilities halves HP cost and grants 2 extra MBP (or less).
Flying at or under 9 CR is worth 2 MBP

Attacks that are area effects (1/2 damage on save) should be assumed to hit more than 1 target; multiply their effective damage before calculating their cost.

Various other abilities have costs. You can wing it, or you can look them up in the monster building rules in the DMG and translate it to AC/ATK (at 1 MBP per AC/ATK).

---

I'm going to make a CR 5 moon griffon. I get 21 points (5*4, plus 1 bonus for CR 5).

I start with a Griffon

It gets 18 strength (1 MBP)
It flies (2 MBP)
It has 12 AC (-2 MBP)
Its attacks deal 1d8+4 radiant damage (beak) and 2d6+4 radiant damage (claws) (19.5) (2.5 MBP)
It has 59 HP (4.3 MBP)
(note: 7.8 MBP; the Griffon is CR 2, as expected)

Then I boost it:
It is invisible unless in sunlight (4 MBP for advantage on both attacks and defenses; I assume it doesn't engage in sunlight. PCs with sunlight powers are rare at level 5ish)
It is resistant to weapon damage and immune to radiant damage (4 MBP, +4.3 MBP from double HP cost)
Radiant Aura: creatures who on their turn approach within 10' end their turn there, take 1d10 radiant damage (con save 16 DC for half) 3.7 MBP, discounted by 2 MBP because its effective use is exclusive with flying (1.7 MBP)

Total spent: 21.8 MBP

There we go, a moon griffon. It is a bit over budget.

I'll have to try this out, I usually have to start with an existing monster and then just tweak it. Thanks!
 

NotAYakk

Legend
You should also be able to use this to tweak existing monsters without recalculating.

Instead of calculating the full moon griffon, you are adding 3 CR and passing CR 5 for 13 MBP.

You then pay for the bottom deltas only. Invis (4) Resist (7.4) aura (1.7) for 12.1 points. Maybe up damage by 3.5.
 


NotAYakk

Legend
Ok, I would hardly call this "ridiculously simple". I've used the CR system in the DMG many times and this actually looks more convoluted so I'll have to examine it more in detail when I have time.
It is possibly more complex to use this to take a monster and determine its CR.

I believe it is a lot simpler if you say "I want a CR 7 giant cosmic chicken that fires laz0rs from its eyes".

Free:
10 attack stat
0 standard attack damage
0 HP
10 AC
Proficiency: +3

Budget: 43 MBP.

AC: 11 (1 MBP) -- feathers are poor armor.
HP: 100 (+12.5 MBP) -- round number to start
Strength and Charisma: 20 (5 MBP) -- what, you don't like chickens?
Cosmic Beak and Claw: +8 attack, 1d6+5 piercing, 1d8+5 slashing (18) (6 MBP)
Legendary Resists: 3 (4 MBP) -- the legend of the laz0r chicken
Legendary Actions (3): Pew Pew creature whose turn just ended must make a Dex save DC 16 or take 2d8+5 radiant damage (14*3=42) 14 MBP

Total 42.5 MBP.

If we don't think it is tough enough (11 AC and 100 HP is a bit low), bump it to CR 9. That earns us ~8 more MBP and 64 more HP (and 1 more point of proficiency).
 
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GMMichael

Guide of Modos
Ok, I would hardly call this "ridiculously simple". I've used the CR system in the DMG many times and this actually looks more convoluted so I'll have to examine it more in detail when I have time.
Agreed. The MBP list isn't what I would call "ridiculously simple" (the term "weighted average" is in there). I'm not saying that it doesn't work like a charm, though.

Ridiculously simple would be: prep the skin of the monster you want. Slap it on the Stat Block of a similar monster with a party-appropriate CR. Done.

XP for building and sharing!
 

NotAYakk

Legend
Agreed. The MBP list isn't what I would call "ridiculously simple" (the term "weighted average" is in there). I'm not saying that it doesn't work like a charm, though.

Ridiculously simple would be: prep the skin of the monster you want. Slap it on the Stat Block of a similar monster with a party-appropriate CR. Done.

XP for building and sharing!
Ok, I replaced "weighted average" with "take the average, or throw out the one that is less important". The impact of attack bonus on monster CR (as dicated by the DMG) is small enough it doesn't matter much.
 

Ancalagon

Dusty Dragon
Agreed. The MBP list isn't what I would call "ridiculously simple" (the term "weighted average" is in there). I'm not saying that it doesn't work like a charm, though.

Ridiculously simple would be: prep the skin of the monster you want. Slap it on the Stat Block of a similar monster with a party-appropriate CR. Done.

XP for building and sharing!
I came here to say the same thing.

A while back, the party, in my Yoon-Suin game, encountered a hostile giant slugman. I didn't have the stats in 5e but I had a rough idea of how dangerous this thing was. So I used hill giant stats.

Could I have spent an hours meticulously stating it out? Sure! But to what gain? The players were none the wiser and the encounter ended on round 2 when the warlock cast fear on the giant slugman.
 

DND_Reborn

Legend
It is possibly more complex to use this to take a monster and determine its CR.
I guess this is more what I am looking for. I want to be able to speck out a stat block and be able to determine the CR.

"Building" like this system and the one in the DMG to me are about the same. I think your outline might be better in the process, but as I'm familiar with the DMG version I don't see it as much "simpler".

But, keep working on it. Provide some more examples. This might help myself (and any others) see your vision more clearly. I know I'll keep looking it over and maybe once I am more familiar with it, I will agree with you.

However, I would still refrain (in any case) from thinking of this as ridiculously simple. 🤷‍♂️
 

I writte here only to ask: has the petitioner monster template (3rd Guide of the Planes) been fixed? It was maybe the most broken monster template in 3rd Ed.
 



NotAYakk

Legend
Well, @LuisCarlos17f 's question did give me a though. You can use this to create 3e style templates.

Lets see if it works reasonably well.

Half Dragon
+4 strength, +4 intelligence, +4 charisma, +4 constitution
+2 AC (scales)
Size grows by 1 (HD increase)
Fly speed equal to your ground speed
Magic resist if CR 9, or could already fly.
Immune to one element type, resistant to another (depending on dragon breed)
Bonus action breath weapon (1d8 damage per 2HD (round up), Charisma-based DC, area large enough to hit 2 creatures, recharge 6)
Divide HD by number of attacks and divide by 3; round down. Gain that many 1d6 elemental damage on your attacks.
+2 damage/tap if strength based

---

I'll assume +2 to your primary stat (2 MBP)
+2 AC (2 MBP)
Fly speed (2 MBP if CR 9 or under) or magic resist (2 MBP if CR 9 or higher)
+2 HP/HD (0.25 MBP/HD)
HD grows by 1 (1 HP/HD) (0.125 MBP/HD)
9 bonus damage per 2HD (0.5 MBP/HD)
3.5 DPR for every 3 HD (0.4 MPB/HD)
2 DPR/tap (2-6 MBP)
Total: about 1.25 MBP/HD

Total: 8-12 MBP plus 1.25 MBP/HD.

But multiple attacks correlates with more HD, so...

CR impact: +2 CR, +1 for every 3 HD.

...

Half-red dragon griffon. 7HD: so CR 2+2+7/3 = CR 6.

Huge Draconic Beast
14 AC
22 strength
20 constitution
12 charisma
7d12+35 HP (80 HP)
Magic resistant
Immune to Fire
Resistant to Cold
Beak: Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 10 (1d8 + 6) piercing+ 3 (1d6) fire damage.

Claws: Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing + 3 (1d6) fire damage.

Bonus Action Breath Weapon: DC 12 dex save for 4d8 (18) fire damage (save for half)

...

It does constrain the template design if you want it to be able to calculate CR changes without basically rebuilding it.
 

Cleon

Adventurer
As a reverse-reverse-engineering test I ran a couple of SRD creatures through this formula and they came out with a CR a notch too low.

Bugbear is AC 16 (6 MBP), 24 hp (3¾ MBP), +2 in attack stat (2 MBP), 11 attack damage (3⅔ MBP) for a total of a hair over 15 MBP which is, what Challenge 0 and a bit (1/2? 1/4?) rather than the 18 MBP the formula uses for Challenge 1 creature.

Giant Constrictor Snake should be MBP 22 since it's Challenge 2, but its AC 12 (2 MBP), 60 hp (7½ MBP), +4 attack stat (4 MBP) and 13 damage (4⅓ MBP) come to 17.833, or pretty the formula's figure for Challenge 1 (18 MBP).

Hmm, I can't find anything in the DMG guidelines for costing a monster with save-or-die / save-or-suck powers such as a Basilisk's petrifying gaze or a ghoul's paralysing claws. Guess we'll just have to wing those!
 

overgeeked

B/X Known World
It looks good as a detailed monster builder and you clearly put in a lot of work, but I gotta agree about the simplicity claim.

Use the “5E Monster Manual on a business card” numbers as your baseline and eyeball any adjustments from there. Drop those numbers into a spreadsheet once and you only have to reference it going forward. Coming up with a monster idea takes longer than “building” one from those numbers.
 


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