what class for this BBGirl ?

Hello there,
I'm running the CoCT AP with 6 players. They just finish the 3rd book and are moving to kaer Maga. I wanted to add some challenge during their journey and came up with an Half gargoyle - half succubus concept (from demon revisited).
The girl is quite a big bad girl imho. I really like her ability to turn back into stone with a man crushed between her arms... anyway, This monster is only a CR6 and She will not have a chance in front of the group. So I decided to give her some class level. But which one ?
any suggestion ?

for your information: here she is:

Gargoyle-Half succubus CR6
CE Medium outsider (earth, evil)
Init +7; Senses darkvision 60 ft.; Perception +1

DEFENSE

AC 18, touch 13, flat-footed 15 (+3 Dex, +5 natural)
HP 52 (5d10+25)
Fort +9, Ref +7, Will +5
DR 10/magic; Immune poison, acid, cold, electricity; SR 16; Resist fire 10

OFFENSE

Speed 40 ft., fly 80 ft. (good)
2 claws +7 (1d6+2), bite +7 (1d4+2), gore +7 (1d4+2)

Space 5 ft., Reach 5 ft.
Special Attacks passion, smite good,
Spell-Like Abilities darkness 3/day, detect thoughts,

STATISTICS

Str 15, Dex 16, Con 20, Int 8, Wis 13, Cha 15
Base Atk +5; CMB +7; CMD 20
Feats Improved Initiative, Hover, Skill Focus (Fly)
Skills Stealth +11, Perception +5, Fly +12
Racial Modifiers +2 Stealth (+6 in stony environs)
Languages Common, Terran
SQ freeze, change shape

what level is the party? Whats its makeup? if you want to challenge your party its a good idea to know what they can do.

That said, I'd recommend the best way to add to the challenge is to give her a sister. Single monster encounters are generally not a good idea for a party of 4 or more.

8 Intelligence? That doesn't work with my idea of succubi at all. Succubi are supposed to be conniving, deliciously devious ladies who tempt and lead astray poor souls before devouring their energy.

Hard to think someone with sub-human intelligence could act with that level of finesse, high Charisma notwithstanding.

Give her some levels of sorceress (Abyssal Bloodline, obviously). Make her an enchantress with charm person, deep slumber and dominate person, depending on how high level she is and how strong your party is.

Tetori Monk levels, more ac/saves/ki points and grappling, make that kiss really the star.

8 Intelligence? That doesn't work with my idea of succubi at all. Succubi are supposed to be conniving, deliciously devious ladies who tempt and lead astray poor souls before devouring their energy.

Hard to think someone with sub-human intelligence could act with that level of finesse, high Charisma notwithstanding.

8 INT is not sub-human. It's a bit lower than average, but it's not anywhere as low as you are making it sound. 26% of all results on a 3d6 distribution are 8 or lower.

And there can be women who are evil and devious without being all that smart. I've met a few of them.

Ditto on party composition. A party of 6 is already above the curve with thei force advantage. What level, race, class, build, etc...

I like the concept...sadly this garbus seems a bit weak. Though elemental-based casters will be twiddling their thumbs. Well save for good fire builds. Her defenses are way too low for any kind of optimized group. Unless they are all lightning casters :)

Why no social skills? What is her motivation?

What does the passion ability do? Unless it is game changer she really sems to be lacking any kind of main offense. 28 points max from her full attack which I doubt she'll be doing if she is only +7 to hit. I ran into a ghoul in a level 1 Society module whose full attack could do 38 points, before crits. And of course paralyze.

At best, in an ambush situation, at night, with her darkness up and the party not having daylight, dispel or darkvision available and if she had some bonus dice (say a couple levels of rogue) with her smite on, yeah it may be something...but otherwise...meh.

hello ! thank you for your comments.
first of all: the group is level 6 but they are built with 23pt (as far as I can remember): there is one ceric, magus, cavalier archer, wizard (evocation), bard and alchemist. They are quite efficients.
for exemple they put down the Rakshasa in the vivified labyrinth without too much trouble. So a CR from 8 to 10 should do.

Now about her (any idea of a name BTW ?)
8 of int is because of the gargoyle part that is quite numb... (half fiend get +2int)...but this is also why I have so much trouble finding what to do with her.
No social skill yet because I just created her with the basic rules (applying the half fiend succubus template to the gargoyle). I will add them with the class's skillpoints.

for her special abilities:
Freeze (Ex) A gargoyle can hold itself so still it appears to be a statue. A gargoyle that uses freeze can take 20 on its Stealth check to hide in plain sight as a stone statue.
passion (Su) A half-succubus drains energy from a mortal she lures into an act of passion—unwilling victims must be grappled before the half-succubus can use this ability. The passion bestows one negative level. A half- succubus can use this ability a number of times per day equal to her Hit Dice. The save DC to remove one of these negative levels is equal to 10 + the half-succubus’s HD + her Cha modifier.
change shape (Su) A half-succubus can use this ability to assume the form of any humanoid creature of her size, as if using alter self, once per day.
smite good (Su) Once per day, as a swift action, the half-fiend can smite good as the smite evil ability of a paladin of the same level as the half-fiend’s Hit Dice, except affecting a good target. The smite persists until target is dead or the half-fiend rests.

I was also thinking about rogue, but monk could be fun too.

Her secret goal is to take control of all the wild gargoyles that lives close to kaer Maga.
I was thinking about her abilities to "shape change" to introduce her to the group as a victim of some bandits. She will present herself as a "commercial facilitator" sent by the dwarves to help them negociate the purchase of a couple of golems in the Prison-city. So obviously, bluff and diplomacy will be my choice.

-sorcerer. I also though about that but she will not gain any bonus from her bloodline :/
-a (twin) sister. I could consider that too