My Baddie's Threat Level?

[rockdeworld]

Link to character sheet here: http://www.myth-weavers.com/sheetview.php?sheetid=299638

My group: I'm DMing a campaign that uses Frank & K rules, and Pathfinder skills. Since the players aren't minmaxers by any stretch of the imagination, they're probably playing on Tier 2-3 with a Tome Ranger (http://www.dnd-wiki.org/wiki/Ranger,_Tome_%283.5e_Class%29), Fighter (http://www.dnd-wiki.org/wiki/Races_of_War_%283.5e_Sourcebook%29/Warriors_with_Class#Fighter), Gadgeteer (http://www.dnd-wiki.org/wiki/Book_of_Gears_%283.5e_Sourcebook%29/Mechanics_with_Class#Base_Classes), and possibly Samurai (http://www.dnd-wiki.org/wiki/Races_of_War_%283.5e_Sourcebook%29/Warriors_with_Class#Samurai) (still haven't got the last guy figured out yet). All players are level 10. The gadgeteer specializes in using a fuel-efficient flamethrower invention every round for 10d6 damage a pop, the ranger is a gish, and the others are straight melee.

My baddie: I don't have Warforged stats, so I whipped up a construct template with no LA or HD, and that's pretty much it.
Level 7 Wizard (Specialize: Necromancy, Banned: Enchantment, Evocation)
HP: 39
STR 10, DEX 14, CON -, INT 20, WIS 10, CHA 18
FORT -, REF +4, WILL +5
Feats: Scribe Scroll (bonus), Combat Casting (Frank&K), Army of Demons (Frank&K), Craft Wondrous Item (bonus), Whispers of the Otherworld (Frank&K)
Items: Headband of Intellect +2, Cloak of Charisma +2
Spells:
1/Ray of Enfeeblement (None, Ranged Touch) 1/1
Shield 1/1
Mage Armor 1/1
Grease (Reflex) 4/4
2/Invisibility 2/2
Ghoul Touch (Fort) 1/1
Glitterdust (Will) 2/2
3/Protection from Energy 1/1
Stinking Cloud (Fort) 1/1
Fly 1/1
Major Image 1/1
4/Black Tentacles (None, Grapple) 1/1
Solid Fog (None) 1/1
Enervation (None, Ranged Touch) 1/1
SQ: Low-light vision.
Darkvision out to 60 feet.
Immunity to all mind-affecting effects (charms, compulsions, phantasms, patterns, and morale effects).
Immunity to poison, sleep effects, paralysis, stunning, disease, death effects, and necromancy effects.
Cannot heal damage on his own, but can be repaired
Not subject to critical hits, nonlethal damage, ability damage, ability drain, fatigue, exhaustion, or energy drain.
Immunity to any effect that requires a Fortitude save (unless the effect also works on objects, or is harmless).
Permanencied Detect Magic

Minions: 3 Wraith (Whispers of the Otherworld)
1 Wight (Whispers of the Otherworld)
15 Lemure Devils (Army of Demons)
1 Imp Devil (Army of Demons)
1 Shadow Mastiff (Army of Demons, Cohort)
20 Human Skeletons
8 Human Zombies
All undead have +2 Init, +4 Move Silently, and Lifesight

Tactics: Precombat: Shield, Mage Armor, Protection from Energy (Fire) Invisibility, Fly
1st round: Black Tentacles, tell minions to attack
2nd round: Solid Fog
3rd round: Stinking Cloud
4th+ round: Glitterdust, Grease, Enervation as needed

Here's my question: how does this baddie stack up against the PCs? Specifically, will either group dominate the other? Will he prove a reasonable challenge, or be too weak? I don't really have anyone to playtest him with, so I'm hoping you guys can help me figure this out.

[Amphetryon]

Frank & K Tome series may seem pretty overpowered if the group really isn't minmax oriented.

Your baddie specializes in BFC, which your players may have great difficulty in overcoming unless they're very familiar with the rules-set and the Tomes, both.

You could be setting up your players for a very difficult fight.

[rockdeworld]

That's what I was afraid of. I don't want a TPK, ideally the gadgeteer will remain alive (because he can raise the others), but everyone will be near-dead or dead. In that case, what's the best way to tone the power down? Spell selection is my first choice. Would banning another school to allow evocation and blasting in battle (enervation, fireball, scorching ray) create a survivable battle?

[Amphetryon]

BFC is REALLY difficult for inexperienced players to overcome, often more difficult than "Save or Lose" effects like Hold Person, because they change the entire field at once rather than just giving a single PC a bad day. Solid Fog + EBT, in particular, is a fairly brutal lockdown/damage combo where you essentially force your PCs to either have some sort of FOM or just accept that they'll be repeatedly grappled and attacked by Naruto-monsters. If Hank gets taken out of the fight by a single spell or spell combo, it can create urgency for the PCs; if Hank, Diana, Presto, Eric, and Sheila are all taken out by a single spell or spell combo, it just creates a bad encounter for all of them with a nigh-unwinnable fight for poor Bobby and Uni.

Given your PCs, I'd consider swapping the vast majority of BFC spells for a mix of multi-target blasting spells and single target Save or Lose/Suck spells. You'll be less likely to turn the action economy on its ear that way, and the mix will keep it from feeling like you've got it in for one of your PCs.