Under the Diabolist's imp companion, it says this:
A diabolist’s imp increases in power as the diabolist gains levels according to Table 3–8: Animal Companion Base Statistics in the Pathfinder RPG Core Rulebook, with the following changes.
Class Level: This is the diabolist’s class level plus her highest caster level. This does not stack with class levels that grant an animal companion.
Under RAW, I take this to mean it is diaboloist level+total caster level, including the diabolist levels. My GM and at least one other player (not that I was arguing) say this is not RAI, and disallowed it. But I am wondering if this is RAI, because it seems to me that the other diabolist class features, plus the frailty of a normal imp, are weak enough to actually allow this.
What are the thoughts of the paizonian community???
Could anyone give me an opinion on this? I kind of have a deadline.......
I don't see any other way to read that sentence than the way you did. At first glance it certainly seems odd that the diabolist levels serve "double duty", but it may be balanced anyway.
I haven't got any experience with diabolist characters (as player or DM), so I can't really provide any advice.
I do not think they mean the game term "caster level" but are actually referring to you highest level in a casting class other than diabolist.
Example:
Wizard 5/diabolist 4 (don't kill me if this is a bad example...I just threw in the numbers)
So for the purposes of the imp you add your wizard level to your diabolist level (5+4=9) and that's the level that it progresses at.
If you had some odd multi-class start, say...
Sorc 2/Wiz 3/ Diabolist 4
Then you would add your Wiz level to your diabolist level and ignore your Sorc levels for the Imps progression.
I think the intent is for it to be:
the highest caster level you have + your diabolist level.
I don't think the intent is to allow your level for the imp to be higher than your own level.
I do agree that its poorly worded.
-S