Spell Resistance and Class Levels

[Jhulae]

I know that races like Drow get SR equal to 11+character level (meaning a 10th level Drow cleric would have an SR of 21).

Lets say I now want to make a 6th level BBEG Succubus Cleric. Succubi have a 'stock' SR of 18. Do they also add their class levels to their SR like Drow (as above) for a total SR of 24 or does it just stay at 18?

EDIT - I found the answer. It goes up. The Hound Archon entry has the Hound Archon Hero sub-entry, showing an 11th level paladin Hound Archon. The SR of the HA (16) goes up to 27 as an 11th level Paladin.

 

[moritheil]

Lets say I now want to make a 6th level BBEG Succubus Cleric. Succubi have a 'stock' SR of 18. Do they also add their class levels to their SR like Drow (as above) for a total SR of 24 or does it just stay at 18?

EDIT - I found the answer. It goes up. The Hound Archon entry has the Hound Archon Hero sub-entry, showing an 11th level paladin Hound Archon. The SR of the HA (16) goes up to 27 as an 11th level Paladin.

There are also examples where it does not go up with class levels, and instead only improves with racial HD. I don't recall any offhand, but two years ago I had to look into the matter for a campaign full of monster races, and based on the evidence the ruling was that only racial HD increase things like SR and caster level of racial (Sp).

Of course, in cases where it specifically says it goes up, this is a nonissue.

 

[the Jester]

As a dm who uses a huge number of advanced monsters in an epic campaign, I go on a case by case basis. Is the SR a big part of the monster's shtick? Then I'll prolly increase it by +1 per additional CR (NOT by HD!!!!). If not, then I'll leave it. I'm all for custom feats for my monsters to increase that kind of thing- not to mention custom monstrous prestige classes. Heck, a monstrous prc based on increasing your existing SR, DR and other defenses would be pretty interesting.