CR calculations

[Three_Haligonians]

Hey all,

The 3.5 DMG tells us that two creatures of the same CR is equal to that CR +2. So that two CR 3 creatures (say a pair of hell hounds), is a CR 5.

That being said, I have always extrapolated this system when designing my multiple-creature combat encounters. An example being that 4 hell hounds would be a CR 7 (two CR 3 equal 5 and since there are two CR 5's that equals a CR 7). However, if you keep this up then 8 hell hounds are CR 9, 16 are CR 11, 32 CR 13 and 64 CR 15. (That is a lot of hell hounds..)

My question is, since the process of CR is obviously not an exact science - how far would you take the above system before you considered it to be no longer accurate? Once you've reached that limit, how do you adjudicate the CR for higher numbers? What creatures do you think should not apply to this rule? (either because they are weaker or stronger than normal in great numbers).

Thanks,

J from Three Haligonians

 

[Thanee]

The 3.5 DMG tells us that two creatures of the same CR is equal to that CR +2. So that two CR 3 creatures (say a pair of hell hounds), is a CR 5.

Nope.

2x CR X ~ EL X+2 !

CR remains untouched.

My question is, since the process of CR is not an exact science - how far would you take the above system before you considered it to be no longer accurate? Once you've reached that limit, how do you ajudicate the CR for higher numbers? What creatures do you think should not apply to this rule? (either because they are weaker or stronger than normal in great numbers).

There is a table in the DMG, which lists many combinations and some of these limits.

Bye
Thanee

 

[Coredump]

My question is, since the process of CR is obviously not an exact science - how far would you take the above system before you considered it to be no longer accurate?

About 4 of them. Much past that you have to look at the situation because their CR becomes much lower than the ECL of the party, so if the monsters can't hit, it doesn't really matter how many of them there are....

 

[the Jester]

It becomes more and more circumstancial the more creatures you have, but I think it extrapolates pretty well at least up to eight creatures of the same type. If you have a mixed group of creatures of the same CR, I think it works much better- for instance, 32 CR 7 creatures as EL 17 works much better as a group of mixed 7th-level wizards, clerics, fighters and bards than as a band of 32 of the same class. A party of 17th level pcs can rip 7th level npcs to shreds.