CR Calculation [Archive] - Wizards Community

CR Calculation [Archive] - Wizards Community

Post/Author/DateTime Post
elenril
10-03-06, 04:41 PM Is there a formula for calculating CRs? I have plans for creating some of my own monsters and would love to have a way (other than just extensive play testing) to determine what the CR would be.

Thanks,
elenril
frasmage
10-03-06, 04:57 PM CR calculator, as in assigning a difficulty to a new creature or as in determining how many already defined creatures to send against the party? I assume you mean the first of those, but I am not aware of any

You could check yabathewhat's feature point system (http://boards1.wizards.com/showthread.php?t=667683), but thats mostly for determining level adjustment for races, so that might not be what your looking for.

For determining CR's it is more of a guideline of how easily the party can handle it and how much damage/depletion of abilities they will take. I would suggest you try to guess, but also make sure you have a "kill switch" or player control advantage trigger (using the dungeon environtment), in case it does get out of hand
The_Jester
10-03-06, 06:57 PM Trial and error.

A few things you can do:
A monster minus all it's special abilities should be pretty much an NPC class in respect to feats and skill points and ability bonuses. So take the maximum HD and divide that in half.
That's the very, very basic CR.
Then you add a bonus for stats above and beyond average. Gnolls get a CR bonus because of high ability scores despite lacking any special powers. Then assign bonuses to CR for each special or magical ability they have ranging from +1/4 for really minor and weak abilities that have little bearing on their challenge to +2 for kick-butt special talents.
Add it all up, round down for fractions.

If the monster has some really, really strong weaknesses (destroyed by sunlight, double damage from fire attacks, etc) feel free to knock the CR down by 1/2 to 1.

Then compare it to other monsters of the same general toughness and see how it compares. Maybe pit a few together to see what happens.
CharlieRock
10-04-06, 08:01 AM Trial and error.

A few things you can do:
A monster minus all it's special abilities should be pretty much an NPC class in respect to feats and skill points and ability bonuses. So take the maximum HD and divide that in half.
That's the very, very basic CR.
Then you add a bonus for stats above and beyond average. Gnolls get a CR bonus because of high ability scores despite lacking any special powers. Then assign bonuses to CR for each special or magical ability they have ranging from +1/4 for really minor and weak abilities that have little bearing on their challenge to +2 for kick-butt special talents.
Add it all up, round down for fractions.

If the monster has some really, really strong weaknesses (destroyed by sunlight, double damage from fire attacks, etc) feel free to knock the CR down by 1/2 to 1.

Then compare it to other monsters of the same general toughness and see how it compares. Maybe pit a few together to see what happens.
Indeed!
Also, the CR of a creature is not unmodifiable. Ten orcs unarmed and slumbering in the bottom of a pit are less CR then ten orcs with full battle-rattle. Unless the PCs are the ones that arranged for them to fall into the pit and doze off, they get less credit for the orcs defeat. If that sounds too crazy, disregard it :)
metalmorphosis
10-04-06, 09:01 AM -OR-
And I know this may be a stretch here...

You could look at chapter 5 of the Monster Manual - Making Monsters
:D
CharlieRock
10-04-06, 09:03 AM Thats Cheating :P
The_Jester
10-04-06, 12:48 PM Indeed!
Also, the CR of a creature is not unmodifiable. Ten orcs unarmed and slumbering in the bottom of a pit are less CR then ten orcs with full battle-rattle. Unless the PCs are the ones that arranged for them to fall into the pit and doze off, they get less credit for the orcs defeat. If that sounds too crazy, disregard it :)

That's really Encounter Level. Situational modifiers and group size affect the EL raising it up or down.
Hell_Bane
10-04-06, 01:29 PM Savage Species deals with that.
metalmorphosis
10-04-06, 01:42 PM Ok... just piddling around. Here's a link I came across:

www.enworld.org/cc/fiend_factory/cr_calculator.php

I don't know how useful it is cause the site is blocked by the filters here at work, but it reads like it'd be something that would work.
elenril
10-04-06, 04:13 PM Is that in the version 3.0 Monster Manual? Or just the 3.5? Hmm, I'll have to check that out when I get home. If that's the case I'm a bit embarassed :">

Thanks,
Elenril
elenril
10-04-06, 04:16 PM Thanks for link! That's the kind of thing I'm looking for!

Thanks,
Elenril
metalmorphosis
10-04-06, 04:17 PM Is that in the version 3.0 Monster Manual? Or just the 3.5? Hmm, I'll have to check that out when I get home. If that's the case I'm a bit embarassed :">

Thanks,
Elenril
heh... it's in the 3.5 MM.
3.0 doesn't have it.

Post/Author/DateTime	Post
elenril 10-03-06, 04:41 PM	Is there a formula for calculating CRs? I have plans for creating some of my own monsters and would love to have a way (other than just extensive play testing) to determine what the CR would be. Thanks, elenril
frasmage 10-03-06, 04:57 PM	CR calculator, as in assigning a difficulty to a new creature or as in determining how many already defined creatures to send against the party? I assume you mean the first of those, but I am not aware of any You could check yabathewhat's feature point system (http://boards1.wizards.com/showthread.php?t=667683), but thats mostly for determining level adjustment for races, so that might not be what your looking for. For determining CR's it is more of a guideline of how easily the party can handle it and how much damage/depletion of abilities they will take. I would suggest you try to guess, but also make sure you have a "kill switch" or player control advantage trigger (using the dungeon environtment), in case it does get out of hand
The_Jester 10-03-06, 06:57 PM	Trial and error. A few things you can do: A monster minus all it's special abilities should be pretty much an NPC class in respect to feats and skill points and ability bonuses. So take the maximum HD and divide that in half. That's the very, very basic CR. Then you add a bonus for stats above and beyond average. Gnolls get a CR bonus because of high ability scores despite lacking any special powers. Then assign bonuses to CR for each special or magical ability they have ranging from +1/4 for really minor and weak abilities that have little bearing on their challenge to +2 for kick-butt special talents. Add it all up, round down for fractions. If the monster has some really, really strong weaknesses (destroyed by sunlight, double damage from fire attacks, etc) feel free to knock the CR down by 1/2 to 1. Then compare it to other monsters of the same general toughness and see how it compares. Maybe pit a few together to see what happens.
CharlieRock 10-04-06, 08:01 AM	Trial and error. A few things you can do: A monster minus all it's special abilities should be pretty much an NPC class in respect to feats and skill points and ability bonuses. So take the maximum HD and divide that in half. That's the very, very basic CR. Then you add a bonus for stats above and beyond average. Gnolls get a CR bonus because of high ability scores despite lacking any special powers. Then assign bonuses to CR for each special or magical ability they have ranging from +1/4 for really minor and weak abilities that have little bearing on their challenge to +2 for kick-butt special talents. Add it all up, round down for fractions. If the monster has some really, really strong weaknesses (destroyed by sunlight, double damage from fire attacks, etc) feel free to knock the CR down by 1/2 to 1. Then compare it to other monsters of the same general toughness and see how it compares. Maybe pit a few together to see what happens. Indeed! Also, the CR of a creature is not unmodifiable. Ten orcs unarmed and slumbering in the bottom of a pit are less CR then ten orcs with full battle-rattle. Unless the PCs are the ones that arranged for them to fall into the pit and doze off, they get less credit for the orcs defeat. If that sounds too crazy, disregard it :)
metalmorphosis 10-04-06, 09:01 AM	-OR- And I know this may be a stretch here... You could look at chapter 5 of the Monster Manual - Making Monsters :D
CharlieRock 10-04-06, 09:03 AM	Thats Cheating :P
The_Jester 10-04-06, 12:48 PM	Indeed! Also, the CR of a creature is not unmodifiable. Ten orcs unarmed and slumbering in the bottom of a pit are less CR then ten orcs with full battle-rattle. Unless the PCs are the ones that arranged for them to fall into the pit and doze off, they get less credit for the orcs defeat. If that sounds too crazy, disregard it :) That's really Encounter Level. Situational modifiers and group size affect the EL raising it up or down.
Hell_Bane 10-04-06, 01:29 PM	Savage Species deals with that.
metalmorphosis 10-04-06, 01:42 PM	Ok... just piddling around. Here's a link I came across: www.enworld.org/cc/fiend_factory/cr_calculator.php I don't know how useful it is cause the site is blocked by the filters here at work, but it reads like it'd be something that would work.
elenril 10-04-06, 04:13 PM	Is that in the version 3.0 Monster Manual? Or just the 3.5? Hmm, I'll have to check that out when I get home. If that's the case I'm a bit embarassed :"> Thanks, Elenril
elenril 10-04-06, 04:16 PM	Thanks for link! That's the kind of thing I'm looking for! Thanks, Elenril
metalmorphosis 10-04-06, 04:17 PM	Is that in the version 3.0 Monster Manual? Or just the 3.5? Hmm, I'll have to check that out when I get home. If that's the case I'm a bit embarassed :"> Thanks, Elenril heh... it's in the 3.5 MM. 3.0 doesn't have it.