d20 creature conversion

[peterb]

I’ve been fiddling with a conversion of creatures from the d20 SRD (i.e. from the DnD Monster Manual) to BRP. I need the data for my Creature Generator spreadsheet. Since the data is available in XML and DB formats it’s not that difficult to do a translation. I’ve chosen the quick and dirty route and imported all data into Excel and now I’m almost done with the translation scripts.

When I’m done, creating a word document and a PDF printout of all the creatures won’t be that much trouble, in fact it will just be a matter of writing a VBA script in Word that merges the all the information from the Excel spreadsheets per each creature and stores that as a creature description in a Word document. Before I do that I’d like to see if anyone has any objections to my transformation algorithms.

1) Stats

I base the conversion on the average given in the SRD. The stat is divided by the average dice value and the reminder is added as a dice bonus. The choice of dice is based on the average value.

'---------------------------------------------------------------------------------------

' Procedure : getDiceString

' Author    : Peter Brink

' Date      : 2008-05-10

' Purpose   : The average stat value / 6 would give you the number of dices used. But

'             we dont use more than a handfull dices. We first need to analyze the

'             average value and decide how many dices we will use. We then use the

'             remainder as a point bonus.

'---------------------------------------------------------------------------------------

'

Public Function getDiceString(averageVal As Integer) As String


    Dim noDice As Integer

    Dim diceType As Integer

    Dim diceMod As Integer


    diceType = 6


    Select Case averageVal

        Case 1 To 4 'split in number of d3 and add reminder as +p

            noDice = CInt(averageVal / 1.5)

            diceMod = averageVal Mod 1.5

            diceType = 3

        Case 5 To 10 'split in number of d4 and add reminder as +p

            noDice = CInt(averageVal / 2.5)

            diceMod = averageVal Mod 2.5

            diceType = 4

        Case 11 To 17 'split in 3d6 and add reminder as +p

            noDice = 3

            diceMod = averageVal - 11

        Case 11 To 20 'split in 4d6 and add reminder as +p

            noDice = 4

            diceMod = averageVal - 14

        Case 21 To 40 'split in 6d6 and add reminder as +p

            noDice = 6

            diceMod = averageVal - 21

        Case 41 To 60 'split in 8d6 and add reminder as +p

            noDice = 8

            diceMod = averageVal - 28

        Case 61 To 80 'split in 10d6 and add reminder as +p

            noDice = 10

            diceMod = averageVal - 35

        Case Else 'split in 10d10 and add reminder as +p

            noDice = 10

            diceMod = averageVal - 55

            diceType = 10

    End Select


    If averageVal = 0 Then

        getDiceString = "0"

    ElseIf Not diceMod = 0 Then

        getDiceString = noDice & "d" & diceType & "+" & diceMod

    Else

        getDiceString = noDice & "d" & diceType

    End If


End Function

SIZ is a little bit different matter as it's not given in the SRD. I base the conversion on the broad size category and the STR stat value.

'---------------------------------------------------------------------------------------

' Procedure : getSizDice

' Author    : Peter Brink

' Date      : 2008-05-10

' Purpose   : Uses the STR dice and the Size value of a creature to create it's SIZ dice

'---------------------------------------------------------------------------------------

'

Public Function getSizDice(creatureSize As String, strDice As String) As String


    Select Case LCase(creatureSize)

        Case "fine" 'SIZ 1

            getSizDice = "1"

        Case "diminutive" 'SIZ 1-2

            getSizDice = "1d2"

        Case "tiny" 'SIZ 2-4

            getSizDice = "1d3+1"

        Case Else

            getSizDice = parseStrDice(strDice, creatureSize)

    End Select


End Function

2) Move

I divide the d20 move rate by 10 and drop all reminders, this gives a reliable translation to BRP, IMO.

3) Armour

Here I just parses the armour record and uses the natural AC bonus as a AP value.

4) Skills

I wrote a skill conversion function for the Creature Creator and I use it here to convert a d20 skill to an equivalent BRP skill. The skill ranks are multiplied by 5 and this gives a first rudimentary conversion. However, the skill levels seems a bit high so I'm wondering if I don't need to write a more intelligent conversion routine.

5) Weapons

Same as with skills, the skill rank is converted. This can lead to quite high base chances. But some creatures in RQ also had high base chances. A more general conversion algorithm is probably needed here... The weapon type checked against those I have in the Creator.

6) Hit Locations

I use the categories of hit locations from RQ Creatures. I also need to create a few new ones. No problems here as far as I can see.

7) Description

The description contains of a few sections. The first is just a short description of the creature and that only needs to be extracted. The second is a very brief note on the creature's combat tactics, also only needs to be extracted. Then there are notes about special powers and the like. I don't really plan to keep those - but I haven't decided yet. There are also notes on the creatures skills, or what skills the creature has any racial bonuses in. I'm wondering if one perhaps should use these notes when assessing the average skill values and perhaps that will lead to a better choice of base skill levels.

[nudnic]

That's a great idea. DnD has great monsters.

[frogspawner]

I'm not very familiar with the 3.x monster stats. (Still struggling to find a good way to convert the old MM ones!)

Does your method distinguish AC factors that are due to DEX-type bonuses? They should add to parry and/or dodge skills somehow.

Once you know their CON, how about using their HPs to calculate SIZ?

[peterb]

Does your method distinguish AC factors that are due to DEX-type bonuses? They should add to parry and/or dodge skills somehow.

The d20 SRD has been translated into XML and from there into various DB formats, that's my source. The armour class record for an Aboleth, for example, looks like this:

16 (-2 size, +1 Dex, +7 natural), touch 9, flat-footed 15

This function parses that string and returns the natural AC bonus, which I use as natural AP.

Public Function parseAC(armourString As String) As Integer

    Dim armour As Variant

    Dim tempStr As Variant

    Dim natural As Variant

    Dim cleanedStr As Variant

    Dim apValue As Variant


    armour = Split(armourString, ",")

    apValue = 0


    For Each tempStr In armour

        If InStr(LCase(tempStr), "natural") > 0 Then

            cleanedStr = Trim(tempStr)

            natural = Split(cleanedStr, " ")

            apValue = natural(0)

            apValue = CInt(Right(apValue, Len(apValue) - InStr(apValue, "+")))

        End If

    Next


    parseAC = apValue


End Function[/code]

So, no I don't use the DEX bonuses in my calculation.

Once you know their CON, how about using their HPs to calculate SIZ?

But HP in DnD does not reflect CON + SIZ, at least I have not been able to any such relationship. In 3E all creatures are sorted into a set of Size categories. I base my calculation on that plus the STR value of the creature. SIZ and STR are often somewhat related in BRP.

[frogspawner]

So, no I don't use the DEX bonuses in my calculation.

That's good, then!

But HP in DnD does not reflect CON + SIZ, at least I have not been able to any such relationship.

I think HP is very important for the 'character' of a monster, and should be kept close to the D&D HPs where reasonable. Knowing HP and CON, SIZ would then be defined. Obviously it doesn't work for all D&D creatures: some have more HP/HD than they should from Size alone. So I'd apply some sort of 'cap', according to size category (the extra HD/HP giving extra Dodge capability, say). Or are you taking the view that D&D HPs need to change, being generally too high for BRP?

[peterb]

I think HP is very important for the 'character' of a monster, and should be kept close to the D&D HPs where reasonable. Knowing HP and CON, SIZ would then be defined. Obviously it doesn't work for all D&D creatures: some have more HP/HD than they should from Size alone. So I'd apply some sort of 'cap', according to size category (the extra HD/HP giving extra Dodge capability, say). Or are you taking the view that D&D HPs need to change, being generally too high for BRP?

I try to convert the creatures so that they conform to the normal scale of powers in d100 games. From this follows that I change the HP value of the creatures - so yes I do think the HPs needs to change, they are too high for BRP, IMO.

[frogspawner]

Yes, you're probably right. I prefer to keep the D&D HP values, but that's non-standard and may be too much.

Does your algorithm match creatures already published in BRP well? For example (dragons are too variable)...

T.Rex: STR 10D6+32 (av.67); CON 4D6+21 (av.35); SIZ 6D6+32 (av.53); HP 44; AP 10; Bite 50% 2d6+db; Claw 35% d4+db/2; Kick 45% D6+db.

My way would give 'em 80-90hp (from MM, not sure how many HD they have in 3.x). How about yours?

[Harshax]

I ran 5 or 6 sessions of BRP&D, a fast and dirty conversion to classless d100.

I loved the simplicity of size in D&D. I pretty much doubled HP for each category larger than Medium. Im not sure if I used the same progression in the reverse direction.

Sure, it wasn't as granular as having an actual Size score, but no one semed to mind.

[frogspawner]

I ran 5 or 6 sessions of BRP&D, a fast and dirty conversion to classless d100. ... I pretty much doubled HP for each category larger than Medium.

And a 'slow and dirty' conversion is all I usually run!

But I don't quite understand the conversion you used - how many HP would an 18 HD T.Rex have had in yours?

[peterb]

Yes, you're probably right. I prefer to keep the D&D HP values, but that's non-standard and may be too much.

Does your algorithm match creatures already published in BRP well? For example (dragons are too variable)...

T.Rex: STR 10D6+32 (av.67); CON 4D6+21 (av.35); SIZ 6D6+32 (av.53); HP 44; AP 10; Bite 50% 2d6+db; Claw 35% d4+db/2; Kick 45% D6+db.

My way would give 'em 80-90hp (from MM, not sure how many HD they have in 3.x). How about yours?

From the data in the SRD a Tyranosaurus would have:

STR 10d6+32, CON 6d6+14, SIZ 10d6+48, HP 59, AP 5, Bite 55%.

Because I decided to use the STR value as a base for SIZ some inconsistencies with existing creatures will happen. I figure that most large creatures have more SIZ than STR, but that might be a false assumption on my part... Maybe one should use the average of the average values of STR and CON instead and possibly add or subtract a few points based on size class.

[frogspawner]

Actually, it's pretty close. And where it differs, I like your version better. Higher SIZ, hence more HPs, and more reasonable AP IMHO.

Care to publish any more creatures, for comparision purposes?

[Harshax]

And a 'slow and dirty' conversion is all I usually run!

But I don't quite understand the conversion you used - how many HP would an 18 HD T.Rex have had in yours?

Assume a creature has a CON 15

                    HP          Factor

Colossal            240          16

Gargantuan          120          8

Huge                 60          4

Large                30          2

Medium               15          1

Small                11          0.75

Tiny                 7          0.5

Diminutive           3          0.25

Fine                 1          0.1

[peterb]

Actually, it's pretty close. And where it differs, I like your version better. Higher SIZ, hence more HPs, and more reasonable AP IMHO.

Care to publish any more creatures, for comparision purposes?

Aboleth:

STR: 6d6+5, CON: 4d6+6, SIZ: 6d6+6, INT: 3d6+4, POW: 3d6+6, DEX: 3d6+1, APP: 3d6+6; Move: 1, swim 6; AP: 7; Tentacle 55%; Knowledge (any one) 60, Listen 85, Spot 85, Swim 40.

Creatures like Aboleth and other "high level" creatures tend to have get very high skill bases and that's one of my problems presently - how to get the base chances right.

[frogspawner]

Assume a creature has a CON 15...<snip>

Sorry, you've lost me. I don't have the 3.x MM, so I don't know the size category they give a T.Rex. If it's "Huge", does that mean you'd give it HP equal to CONx4 ? Either way, since I don't know the typical CON either, what would that make it's HP?

[peterb]

Sorry, you've lost me. I don't have the 3.x MM, so I don't know the size category they give a T.Rex. If it's "Huge", does that mean you'd give it HP equal to CONx4 ? Either way, since I don't know the typical CON either, what would that make it's HP?

A T.Rex is "Huge" and have an average CON of 21. So using Harshax's system it would get 84 HP.

The monsters from 3E can be found at Monster Index :: d20srd.org

[frogspawner]

Aboleth:

STR: 6d6+5, CON: 4d6+6, SIZ: 6d6+6, INT: 3d6+4, POW: 3d6+6, DEX: 3d6+1, APP: 3d6+6; Move: 1, swim 6; AP: 7; Tentacle 55%; Knowledge (any one) 60, Listen 85, Spot 85, Swim 40.

Creatures like Aboleth and other "high level" creatures tend to have get very high skill bases and that's one of my problems presently - how to get the base chances right.

Sorry, there's no "Aboleth" in BRP to compare with! How about one/some of these: Alligator, Bear, Brontosaur, Dog, Gorilla, Hawk, Horse*, Lion, Shark, Snake, Giant Squid, Tiger, Wolf. Or: Centaur, Giant, Griffin, Minotaur, Mummy, Orc, Skeleton, Unicorn, Vampire, Zombie, Angel, Lesser Demon, Greater Demon, Elemental.

I know the problem with the attack skills, at least. Previously I based them on HD (all AD&D had!) but that made big things unrealistically (and unsurvivably) good at combat. Currently I just rate them "by hand", according to my idea of the skill of that individual. For big things that's much better, and perhaps explains my willingness to let them have relatively large numbers of HPs (as it makes up for their generally lower 'to hit' chance). But a formulaic method would be useful (particular individuals can always be tweaked, er, individually). Perhaps something like DEXx5?

[frogspawner]

A T.Rex is "Huge" and have an average CON of 21. So using Harshax's system it would get 84 HP.

The monsters from 3E can be found at Monster Index :: d20srd.org

Thanks, that's most helpful. And you had said it was online too - doh!

[frogspawner]

A T.Rex is "Huge" and have an average CON of 21. So using Harshax's system it would get 84 HP.

OK, about the same HP as the 1st-Ed AD&D model (18HD) I'd use. (But about half the new post-arms-race 3.x version: 18HD+99, I see!). I now readily agree that using the 3.x HPs directly is not a viable option!

Best not to extrapolate too much from just one example. Some more examples would be useful here, I'd say.

[peterb]

Griffin

STR: 4d6+4

CON: 3d6+5

SIZ: 4d6+4

INT: 2d4+1

POW: 3d6+2

DEX: 3d6+4

APP: 3d4

Move: 3, fly 8 (average)

AP: 6

Bite 55, Claw 40

Jump 40, Listen 30, Spot 55

A RQ III griffin is much stronger and larger (10d6), it has fixed INT 6, the POW/WIS is the same, and the DEX is quite a bit higher (3d6+12). Animals does not have APP (I need to correct that part of the scripts). Bite is 50 and Claw is also 50. The skills are only half right.

Since RQ III was released (long) before D&D 3E any similarities is not a fault of Chaosiums...

[frogspawner]

A BRP Griffin seems much like in RQ3: STR 10d6, CON 3d6+12, SIZ 10d6, INT 6, POW 3d6+6, DEX 3d6+12, Move 8/12 flying, HP 29, 6AP, Bite 70%, Claw 70%, Dodge 30%, Fly 100% (better than 'average'?), Listen 50%, Sense 65%, Spot 75%.

PS: Clearly BRP/RQ Griffins are 'a cut above' . Horses, Minotaurs and such might match better.

[soltakss]

Animals does not have APP (I need to correct that part of the scripts).

Intelligent creatures should have APP as they can interact meaningfully with other intelligent creatures. An Orc having APP is no different to a dragon or griffin having APP.

Some people might argue that even things like sheep have APP .....

[peterb]

Intelligent creatures should have APP as they can interact meaningfully with other intelligent creatures. An Orc having APP is no different to a dragon or griffin having APP.

Some people might argue that even things like sheep have APP .....

Hm, you do have a point. In RQ (III) animals didn't have any APP. What about BRP? I guess I could include it and people that dislike APP for other creatures than sentients could just ignore it. At the moment I base APP on the average CHA value from d20. Maybe one should standardize and just rule that all non-sentient creatures have an APP of 2d6? But then there are creatures like Unicorns... I think I do like this, I standardize per creature type (which is given in the SRD). So animals get, lets say, 2d6; magical beasts get APP based on SRD CHA; slimes, oozes and such just get 1 and so on.

[frogspawner]

Hm, you do have a point. In RQ (III) animals didn't have any APP. What about BRP?

BRP is just the same and omits APP - but that's a mistake, IMHO. What about manticores, sphinx etc (that even have human faces)? I certainly wouldn't recommend you spend effort removing it from your algorithms.

[peterb]

Mummy

STR: 6d6+3

CON: 0

SIZ: 6d6+3

INT: 2d4

POW: 3d6+3

DEX: 4d4

CHA: 3d6+4

AP: 10 Move: 2

Attacks: Fist 55

Skills: Hide 35, Listen 40, Stealth 35, Spot 40

Here we have an example of how the algorithm STR = SIZ does not work well in all situations. And also how D&D uses CHA in rather strange ways from time to time... I guess they reason that Mummy's are fearsome and that's why they have such an high CHA stat. The AP value is way wrong...

I should note that I already have the statblocks for most creatures from RQ (it's in the MRQ SRD) so I'll be using them instead of the D&D values.

[peterb]

BRP is just the same and omits APP - but that's a mistake, IMHO. What about manticores, sphinx etc (that even have human faces)? I certainly wouldn't recommend you spend effort removing it from your algorithms.

Yeah, I'll just alter the algorithm as I noted in an earlier post up-thread.