Abilities: Special, Extraordinary, Spell Like, Supernatural, Natural, get 'em here.

[JaronK]

The problem I see here is that it speaks specifically to a creature's ability as separate from a classed ability to cast spells. I don't think that passage proves the spellcasting class ability is a special attack. It does define it for non-classed casters though.

Edited to change character's to classed casters. The former was inaccurate.

Please note the Mummy Lord in MM1. It's just a Mummy with 10 Cleric levels. Its spells are a Special Attack, just like everyone else's. See also the Troll Hunter, a Troll with Ranger levels. Again, Special Attack.

So even for spells gained only by class levels, the ability to cast spells is a Special Attack.

Note that there is one funny exception to this... some later books place spells as a Special Quality. That's a bit strange, but irrelevant for our purposes, because Special Qualities and Special Attacks are just subcategories of Special Abilities. So the same necessary rules apply.

JaronK