Challenge Rating Score

[musicman]

In Creating a new module, what is the correct procedure for modifying creatures:

If a Black Dragon has the following stats:

ability stats: 33 - 10 - 23 - 16 - 17 - 16

Dragon level 20

challenge rating 19

Natural AC 30

What would you have to do to make that dragon have a challenge rating of 23?

[kgambit]

You can try by increasing it's age / level. The stats you quote are actually for a epic dragon between a wormling and a very young dragon. or for a non-epic ancient dragon. If you are going for NON-epic - change it to a wyrm or a great wyrm with the following stats:

Great wyrm CR 22:
Size (G) HP 37d12+296 (536) Stats 37 10 27 20 21 20
Base/Grapple attack +37/+62 Attack +46 Saves+28 +20 +25
Breath 24d4 (36) Fear DC 33
AC 42 (-4 size,+36 natural), touch 6, flat-footed 42

http://www.d20srd.org/srd/monsters/dragonTrue.htm#blackDrago n

For EPIC dragons:

Epic dragons, already Colossal+ by the time they reach the great wyrm stage, do not increase in size thereafter. Use the information presented under the epic dragon entry, below, to determine the statistics of a Colossal+ dragon.

Challenge Rating
For standard dragons, CR increases by 2 per additional age category. For epic dragons, CR increases by 3 per additional age category. All other dragon statistics are as presented for dragons in general and specific dragon varieties.

Age Category
A standard dragon gains one “virtual age category” for every 3 Hit Dice it gains beyond the great wyrm stage. Abilities that function once per day per age category or otherwise use the dragon’s age category as part of a calculation use this adjusted number. Epic dragons gain one age category per 5 Hit Dice beyond great wyrm

Armor Class
A dragon’s natural armor bonus increases by +1 for every Hit Die it gains beyond the great wyrm stage. (This rule applies for lesser dragon advancement as well, since natural armor and Hit Dice always increase at the same rate.)

Ability Scores
A great wyrm’s Strength and Constitution scores both increase by +2 for every virtual age category the dragon gains. Its Dexterity remains unchanged. Its Intelligence, Wisdom, and Charisma increase by +2 for every two age categories the dragon gains.


For more details:

Advanced Dragons (http://www.d20srd.org/srd/epic/monsters/dragonAdvanced.htm)

source: www.d20srd.org

So you can't get a CR 23 exactly but you can get a CR 24 by taking a great wyrm one additional age category

That's +2 to strength and con, +1 to int, wis, cha, 0 for dex
+3 for AC
+3 HD
+2 HD for breath weapon
the great wyrm’s damage reduction increases to 15/epic
great wyrm’s caster level increases by 2
advanced dragons receive one feat for every 3 Hit Dice they have. Feats gained after the dragon attains great wyrm status can be epic feats.

[musicman]

Thank - you very much, your reply was very informative. Thanks Again!