Unfortunately, one of the pirmary ways to make a cool effect on a monster that is otherwise 'mundane' is to say that magic works weirdly on it, or it has strange immunities to magic.
This could have the unfortunate effect of further marginalizing mages as combatants. "Oh, great - not only do my spells do diddly-squat to the owlbear compared to an axe, but now I have to overcome Magic Resistance, too. Remind me why I volunteered to play the Wizard?" In fact, this can already be seen in some ways just with the standard monster tropes: the Body Control mage can't do much against a zombie or a golem, but the knight's sword works just fine. (Sure, the golem has DR 10. The knight doesn't care when his average damage is 16.5.)
One solution is just not to use those special properties, and it has its merits. If, instead of making your creature Immune to Mind Control you remove its vitals, it has a wider appeal. Unfortunately, this doesn't work well for monsters that are generally accepted to be humanoid. If your mind-flayer doesn't have a heart, fine. But if your orc doesn't have guts, it's a little weird, and if that holds true for not only orcs but goblins, gnolls, ogres, bugbears and giants, I'd cry foul.
So we're "stuck" with the idea that mundane monster special abilities need a magical basis, but not wanting to further marginalize mages who engage in combat. Where does that leave us?
To answer that question, I asked myself, "Where are wizards and their ilk useful in combat?" and the answer I got was twofold: they buff the damage dealers, and they remove obstacles to them dealing damage.
Enter the idea of a Dispel Magic aura as one answer. Think of it like a cross between an Affliction and a Mana Damper. (Technically, you could probably build it as an Affliction with Aura and Based on Different Attribute: Spell Level, with the effect of "Dispels temporary effects and suppresses permanent ones." Slap on an Area or Emanation enhancement if you want it to be activated by proximity instead of touch.)
The way I envision it is that anyone who touches or is touched by a creature with a dispel magic aura immediately loses all temporary spells placed on him, resisted by the highest (or lowest, or not at all, depending on how much of a pain it is) spell level he has on currently. That Knight was Great Hasted by the Wizard? Not anymore. Oh, also, whoops, but the Continual Light went out.
If the attacker doesn't have any temporary enchantments on, then hitting the creature with a magic weapon temporarily suppresses one level of enchantments on the weapon. (So, for example, if the weapon is a +3 Accuracy +4 Puissance Penetrating Weapon (2) Ghost Weapon Dancing Sword, after it hits it becomes a +2 Accuracy +3 Puissance weapon without any of that other stuff.) Conversely, if the creature hits an opponent, that opponent's armor (or other miscellaneous gear, GM's call) temporarily loses one level of enchanment.
In order to avoid this being a huge bummer, there are a few restrictions. First and foremost, loss of permanent enchantment is purely temporary. I'm leaning toward it being of 1 minute duration, as long enough to cover any but the longest fights, but short enough not to be a hassle out of combat timing. (Different hits stack effects but just reset the timer for easy book-keeping.) Secondly, this only affects spells on other people. Missile spells, area spells, and Regular spells cast on the creature itself act normally, meaning that magic users can still affect it.
Since I'm not trying to sell books, I'm not going to stat up this power according to the RAW. Instead, I'll just note it down like so:
Dispel Magic Aura: This aura suppresses magic. Anyone who touches or is touched by the creature with this power immediately loses all spells cast on himself or being concentrated on at the moment of contact, subject to the resistance of the highest spell level in effect. In addition, any strike on the creature suppresses on 'level' of enchantment on the striking object for one minute, with multiple strikes causing cumulative effect but not cumulative time. Any hit by the creature suppresses one 'level' of enchantment on the armor or miscellaneous gear of the person hit, in the same way.I imagine gnolls in the world of the Temple will have this. After all, they're twisted magical amalgamations of hyena and man, created long ago by an evil archmage as shock-troops to use against his foes.