creatures with spellcasting levels

[Devon]

Hi, folks,

I'm creating a group of aberrations which, much like driders, were spellcasters before they were transformed into their current form. I'm a little shaky on the math used to guesstimate their CR. The examples I have so far are similar in power level to a drider, so they were easy, but I want there to be some more variety.

Should I just ignore their hit points when using the standard calculator, and assume their CR is their spellcaster level plus abilities(+1 to +2) divided by 3?

Thank you,

Devon

[Grazzt]

According to Monte Cook, a monster with spellcasting abilities (i.e, one that can replicate spells, not one with spell-like abilities) should have a CR AT LEAST equal to its spellcaster level.

For example, Monte said that a Nymph should be at least CR 7 because it can replicate druid spells as 7th-level casters.

[Devon]

Yes, I would agree that making it at least the spellcaster level makes sense. I was hoping to discover some quick way to work that into the standard CR equation, but I'm having difficulty reverse-engineering the Drider to figure out how they did it.

Although the Nymph casts as a 7th-level druid, she doesn't have anywhere near the hit points. Having the ability to cast spells is (IIRC) a +2 in the main part of the CR equation.

I'm beginning to think my CR questions would be best solved if I play it by ear during the game. Use the Force, as it were, and not be bogged down by equations.

- Devon