CR Adjust for a Wounded Creature

[Syntallah]

Does anyone have a system for adjusting the CR of a creature who is wounded? I realize that a creature fights just as effectively whether he has 1hp or a 1000hp. That's part of the problem. However, I believe that the system is assuming that a creature will remain 'on camera' for a certain amount of rounds based upon his hit points lasting out. So, if a creature only has half his hit points when the Party encounters it, and they are not using up as much of their resources as they should against, what effect does that have on its CR?

Here's what I have going on:

The Party is about to encounter a dragon wounded in a fight with a competing adventuring group. The group was decimated, but the dragon lives on with about half his standard total. The dragon in question is an Old Black, normal CR 16.

Any thoughts?

 

[frankthedm]

Does anyone have a system for adjusting the CR of a creature who is wounded? I realize that a creature fights just as effectively whether he has 1hp or a 1000hp. That's part of the problem. However, I believe that the system is assuming that a creature will remain 'on camera' for a certain amount of rounds based upon his hit points lasting out. So, if a creature only has half his hit points when the Party encounters it, and they are not using up as much of their resources as they should against, what effect does that have on its CR?

Here's what I have going on:

The Party is about to encounter a dragon wounded in a fight with a competing adventuring group. The group was decimated, but the dragon lives on with about half his standard total. The dragon in question is an Old Black, normal CR 16.

Any thoughts?

It is really a hard guess. An easier fight reduces XP awards rather than CR.

 

[Darklone]

I usually apply half of the missing hitpoints percentage to CR. In your case, half of half is a quarter making the dragon CR12.

This accounts for the possibility that many monsters with 1 hp may still cause a TPK.

 

[Hedgemage]

In terms of judging whether or not a party can handle the dragon, I wouldn't deduct too much from its CR since it still has all its spells, breath weapon, spell resistance, etc.
For determining experience points, I'd definitely reduce the award in porportion to its remaining HP.

 

[shilsen]

For the combat effectiveness of a creature with lowered hp, I just eyeball how much difference it'll make. I'd say an Old Black Dragon at half normal hp is about CR 14-15.

And since XP in my game has no relationship to what the PCs fight, whether they win or lose, or even whether they fight anything, there is no effect on XP.

 

[Giltonio_Santos]

Easy, just divide the XP awarded among the rival adventurers as well!

Cheers,