The Core Rulebook says that monstrous PCs should slowly decrease the CR of their base race as initial abilities granted by their race diminishes in comparative value.
It is recommended that for every 3 levels gained by the group, the monster character should gain an extra level, received halfway between the 2nd and 3rd levels. Repeat this process a number of times equal to half the monster's CR, rounded down. Using the minotaur example, when the group is at a point between 6th and 7th level, the minotaur gains a level, and then again at 7th, making him a minotaur barbarian 4. This process repeats at 10th level, making him a minotaur barbarian 8 when the group reaches 10th level. From that point onward, he gains levels normally.
The question I have is does this rule also apply to NPCs, so if one makes a minotaur barbarian as used in the example, does his CR decrease as it is given levels in a class? And if so does this also apply to templates?
Thanks in advance!
There is a built in fall-off point for non-"key" classes.
See:
http://paizo.com/pathfinderRPG/prd/monsters/monsterAdvancement.html
Last paragraph.
"Step 3: Determine CR
Determining the final CR for a creature with class levels requires careful consideration. While adding a class level to a monster that stacks with its existing abilities and role generally adds 1 to its CR for each level taken, adding classes that do not stack is more complicated.
Table: Monsters with Class Levels gives general guidelines regarding which core classes add directly to a monster's abilities based on its role. Classes that are marked “key” generally add 1 to a creature's CR for each level added. Classes marked with a “—” increase a creature's CR by 1 for every 2 class levels added until the number of levels added are equal to (or exceed) the creature's original CR, at which point they are treated as “key” levels (adding 1 to the creature's CR for each level added). Creatures that fall into multiple roles treat a class as key if either of its roles treat the class as key. Note that levels in NPC classes are never considered key."
I think the idea is that an ogre with a level or two of wizard is not much more powerful then a regular ogre, while a ogre with 15 levels of wizard isn't much more powerful then a 15th level human wizard. If that makes sense?