Well, to add some fuel to the Ability Focus(Spells) debate (which seems to be as old as the first Monster Manual itself), Ability Focus was updated in MM4 and MM5 to include any special ability that allows a saving throw, not just special attacks. Regardless of your stance on what type of special ability spells are, I feel its pretty safe to say that the general consensus is that the natural spellcasting abilities of creatures ARE special abilities. As such, there is no longer any need to reference antiquated monster stat blocks.
The question now comes down to whether you need to specify a particular spell (such as Ability Focus(Finger of Death)) or whether Ability Focus(Spells) gives a +2 save DC to all spells of that creature. Towards that end, I would like to put forward a few examples:
Mindshredder Zenthal from MM3 has Ability Focus (NOT spell-like ability focus) taken for each of its spell like abilities individually. Witchknifes (MM3) also have Ability Focus, taken only for one of its SLAs but not the others, as does the Vitreous Drinker from MM4. Those were the only examples I could find from the books I have at hand of monsters taking ability focus with regards to "lumped" abilities. What I was really hoping to find was something like a beholder with Ability Focus(Gaze) or some other notable counter-example, so if anyone could come up with a creature like that it would be appreciated.
Anyway, I think it should be fairly clear that at least as far as SLAs go, one must take Ability Focus for each individual "spell", which is in keeping with the Spell-Like Ability Focus feat. From there we can use some logical extensions. Obviously warlocks would have to take ability focus for each "spell" individually; to do otherwise would go against all known examples of AF(SLA), the spirit of feat balancing, and the RAW of SLAF. Phaerrim and Sharns, who transform their spellcasting ability into SLAs, would also have to take the feat for each spell individually. Likewise, a wizard who shapeshifts into a phaerrim would have to take the feat individually for each spell. Following the pattern, it would make sense that such a wizard would have to take the feat individually for each spell when not a phaerrim as well, and by extension, all spellcasters have to take ability focus for each spell individually. (And yes, this is a hasty generalization, but I can't find any examples except from SLAs.)
To get back on the main topic, I guess I'll dust off an old Fun Find: Widen Supernatural Ability from Tome of Magic is missing a critical line that appears in Enlarge Supernatural Ability: "A continuous use ability (such as a gaze attack) can only be enlarged for 1 round." This means that any ability widened with Widen Supernatural Ability stays widened for as long as it is active. There are a whole slew of uses for this, though my particular favorite is for aura-like abilities. YMMV on how you interpret 'Using' the ability that you are widening, and whether WSuA can be applied to innate supernatural effects (for a random example, an Atropal's negative energy aura, which can never be turned off, thus might be interpreted as never 'usable').
