D&D 5E Monster Creation

A

Anth

First Post

• Dec 12, 2014

• #1

Could someone check if I understand the monster creation process in the DMG?

Instead of creating a monster from scratch I'll do something simple: give the Tarrasque regeneration of 40 hp/round (as it had in 3E), but at the same time lower the HD so it has the same CR as before.

Tarrasque, gargantuan (d20 for HD), 33 HD, CON 30 (+10), 676 hp, CR 30.

A CR 30 monster should have 806-850 hp, more than the tarrasque, so I guess that it got its hp multiplied by 1.25 for its immunities.
676 x 1.25 = 845 effective hp, that is right on spot.

Regeneration increase the monsters effective hp with 3 times the hp regenerating every round,
3 x 40 = 120 additional effective hp.

The tarrasque has 10.5 (from d20 HD) + 10 (from CON 30) = 20.5 hp / HD.
6 HD = 6 x 20.5 = 123 hp.
So we should lower its hp with 6 HD.
33 - 6 = 27 HD
27 x 20.5 = 553 hp

So a tarrasque with 40 hp genereation, 27 HD, and 553 hp should be equal to the one in the MM.
Have I done everything correctly?

 

log in or register to remove this ad

Lucas Yew

Explorer

• Dec 12, 2014

• #2

Quite likely, yes. And probably more closer to a true CR 30 monster, I'd say.

Oh, don't forget to add a debris throwing ranged weapon attack!

 

aramis erak

Legend

• Dec 12, 2014

• #3

The HP get x1.25 for immunities.
Legendary resistance 3/day adds 3x30=90 HP.
So effectively 935 HP. That's DCR 32, if we follow the progression of the table.
Magic resistance treats its AC as 2 higher than listed. Expected is 19, actual is 25, and effective is 27, for 8 over, or +4 DCR.
Effective DCR should be 36...

OCR
Mutiattack: 36+28+28+32+24 = 148 damage per round (DPR)
Swallow: 2x one critter added to DPR =56+56 = 112 DPR
Legendary Actions: claws x 3, 28x3=84
344 DPR is about OCR31.
But the expected 23 save DC is 3 shy, for -1 DCR.
The attack bonus is 19, but expected is a 14, for +2 DCR...
32 OCR

The Tarrasque is underrated.
It should be (36+32)/2=33... but the system caps at 30.

 

A

Anth

First Post

• Dec 12, 2014

• #4

aramis erak said:

The Tarrasque is underrated.
It should be (36+32)/2=33... but the system caps at 30.

Click to expand...

OK, I see.
So first I have to take away about 7 HD for it to become a CR 30 monster. Then additional 6 HD for the regeneration, so it should have 20 HD and 410 hp.

Oh, and if I understand correctly "throw rock as a giant" is a freebie that doesn't increase its CR.
I just add ranged rock throwing 4d12 + STR 60/240 as a storm giant.

 

A

Anth

First Post

• Dec 12, 2014

• #5

Sorry. I forgot the x1.25 for immunities.
I only take away 6 HD to bring it down to CR 30.
So it should be 21 HD with 430 hp.

 

E

Eejit

First Post

• Dec 12, 2014

• #6

Anth said:

Sorry. I forgot the x1.25 for immunities.
I only take away 6 HD to bring it down to CR 30.
So it should be 21 HD with 430 hp.

Click to expand...

Wouldn't the immunities affect it's base and regenerated HP equally? So they should be a non-factor in this adjustment.

 

aramis erak

Legend

• Dec 12, 2014

• #7

Anth said:

OK, I see.
So first I have to take away about 7 HD for it to become a CR 30 monster. Then additional 6 HD for the regeneration, so it should have 20 HD and 410 hp.

Oh, and if I understand correctly "throw rock as a giant" is a freebie that doesn't increase its CR.
I just add ranged rock throwing 4d12 + STR 60/240 as a storm giant.

Click to expand...

The throw rock as giant isn't part of the multiattack, and doesn't do as much as the multiattack.

Also, don't look to HD; HD are dervived from HP in monsters, not HP from HD.