EXP question

[Nightstorm]

Ok so if I had a 5hd monster, and he has 10 levels of a class he would be an CR rating of 15. But lets say the monster is CR rating of 15 in the book, has no class advancement, BUT does have HD advancement. Does the CR go up with the Advancement of Hd only ? Lets say the book's example is a 4 hd monster [CR 4] than it advances 3 hit die. Is that CR 7?

 

[jeffhartsell]

Monster CR

HD does not equal CR. When you double HD, you increase the CR by 2. Adding levels officially raises the CR 1 per character level. In practice, you have to fudge that. Adding 10 levels of bard is not the same as 10 levels of fighter as far as CR goes.

 

[Chriskaballa]

First off, a correction to you... HD rarely if ever is equal to CR when it comes to monsters. Please do not confuse the two or you will be swiftly smitten by the entire pantheon of deities in the PHB.

To answer your question, in general, following the advancement rules in the Monster Manual, for every 50% of the original HD you add to a creature, it's +1CR.

With regards to monster class advancement: For each level of a PC class a monster gains its CR increases by 1. For NPC classes, the CR increase is (I believe) the NPC class level minus 1.

Forgive me for omitting anything (if I did). I'm tired and I'm quoting without my books.

~~Chris

 

[Archer]

Doubling the HD of a high CR monster makes a much more powerful monster than just adding 2 levels of fighter though officially both result in the same CR.

 

[the Jester]

Doubling the HD of a high CR monster makes a much more powerful monster than just adding 2 levels of fighter though officially both result in the same CR.

I'd argue that adding two feats (from those fighter levels) is arguably as good as doubling the HD in terms of CR. Maybe not in the case of really high HD monsters, but even then it's pretty close. I've been doing a lot with advanced, levelled and templated creatures lately so I've gotten a lot of experience with them- there just aren't enough high-CR critters out there in the books I've got!

 

[Li Shenron]

Doubling the HD of a high CR monster makes a much more powerful monster than just adding 2 levels of fighter though officially both result in the same CR.

I think that doubling the HD is said to be equal to raising the CR by 2 because it is "quite" (notice the quotes!) similar to having 2 monsters of the same kind, which doubles the XP exactly as having +2 CR does.

IIRC...