I can't find very clear rules about how adding class levels affects monster CR in the books, or maybe i just didn't understood clearly. I aim to make more memorable intelligent creatures like dragons or giants.


1 Answer 1


The rules you're looking for are in Bestiary, Monster Advancement, Adding Class Levels:

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.

It's a delicate process, and at times it's more art than science.

That said, in a nutshell, it's CR +1 per class level (if the class fits well with the original monster), or CR +1 per two class levels (if the class doesn't fit that well with the original monster), or CR +1 per class level if the class levels exceed the original racial HD.

  • \$\begingroup\$ okay thanks, but i have a case where it is no clear : if i take a monster with sla (demon, dragon) , remove their ability to cast SLA and add wizard/sorcerer class levels instead, what is their cr ? \$\endgroup\$
    – anonyme
    Mar 25, 2017 at 17:46
  • \$\begingroup\$ @anonyme "More art than science". Unless the SLA is so essential to the original monster it can't function properly without that SLA, there probably shouldn't be any extra changes in CR calculation. Take Succubus for example. Removing its charm monster at-will SLA is a lot different than removing drow's darkness 1/day SLA. But why would you remove a SLA in the first place? \$\endgroup\$
    – MGlacier
    Mar 25, 2017 at 17:57
  • 1
    \$\begingroup\$ mainly for storytelling purpose, like "that demon was a powerful wizard during his life and retained many of his power when he was turned into a demon in his afetrlife" and for give them another spell list and ability than the usual ones \$\endgroup\$
    – anonyme
    Mar 25, 2017 at 18:06
  • \$\begingroup\$ I think that last clause there should be "or 0.5 * CR + 1 per class level if the class levels exceed the original racial CR". For instance, if racial CR is 4 and I add 7 levels of a non-key class, total CR is 4, then increased by 4/2 for the first four class levels, then increased by 3 for the last three class levels, for a total CR=4+2+3=9. This is equivalent to rCR/2 + class levels: 4/2+7=9. Taken literally, your last clause suggests it should be 4+7=11 which isn't right. It certainly should be "racial CR" not "racial HD". (I think rHD is used for some ECL-related stuff, rather than CRs?) \$\endgroup\$ Mar 25, 2017 at 22:58

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