Optimizing a witch slayer's (ToM prc) disjunction ability

[Hirax]

Witch slayer get a supernatural ability at level 5 that costs a swift action to strip magic from a single foe within 30.' It lasts for one round, and during that round, the foe is affected as though they're in an AMF, unless they make a will save. The DC is 20+cha mod. The only ways I can think of to raise the DC or augment the ability are:

Charisma boosting templates and items, of course

The saint template, in addition to a +4 to charisma, increases the DC of spells, supernatural abilities, and pretty much anything else by 2, for a total of +4 to DC

Ability focus for +2.

Sudden ability focus (ToM), though only 1/day, increases it by another +2. It explicitly stacks with ability focus.

Extend supernatural ability (ToM) doubles the duration to 2 rounds.

ToM has a few other feats along these lines that would be useful for other supernatural abilities.

Veil of allure (MIC) raises the DC of CHA based supernatural abilities (among other things) by 2.

Vow of non-violence (BoED) would seem to raise the DC by +4. Not explicitly, but after reading the entry I'd say it definitely works.

What else is there?

edit: just to play up this underrated class a little, in addition to its nice anti-magic user ability, it gets mettle at level 2, full BAB, 2 good saves, and it doesn't have any feats in its entry requirements.
edit2: I decided it would be a good idea to get the name of the class right >_>

[Zaq]

Witch slayer get a supernatural ability at level 5 that costs a swift action to strip magic from a single foe within 30.' It lasts for one round, and during that round, the foe is affected as though they're in an AMF. The DC is 20+cha mod. The only ways I can think of to raise the DC or augment the ability are:

Charisma boosting templates and items, of course

The saint template, in addition to a +4 to charisma, increases the DC of spells, supernatural abilities, and pretty much anything else by 2, for a total of +4 to DC

Ability focus for +2.

Sudden ability focus (ToM), though only 1/day, increases it by another +2. It explicitly stacks with ability focus.

Extend supernatural ability (ToM) doubles the duration to 2 rounds.

What else is there?

edit: just to play up this underrated class a little, in addition to its nice anti-magic user ability, it gets mettle at level 2, full BAB, 2 good saves, and it doesn't have any feats in its entry requirements.
edit2: I decided it would be a good idea to get the name of the class right >_>

The Veil of Allure (MIC) should do it. I don't have the book open, but I'm pretty sure it increases the DC of CHA-based (Su) abilities by 2.

Vow of Nonviolence might do it.

[Person_Man]

You can also debuff their caster level check. Anything that imposes negative levels would work. There's also a bunch of debuff aura's and spells out there, though you'd have to read the specifics to make sure that it's covered.

You might also consider the Mystic Fire Knight Paladin 5 substitution level (Champions of Valor pg 45.). If you successfully use Smite Evil on an enemy, for 1 round afterward it has to make a (moderately difficult, but much easier to debuff) Concentration check to cast any spell or use any spell completion or spell trigger item. You give up nothing to gain this ability (other then having to worship a specific deity). There's also a trick with Sunder or Sleight of Hand - you can just destroy or take their holy symbol or spell component pouch. It obviously doesn't work on enemies with Eschew Materials or Spell-Like and Supernatural abilities, but it should cover many magic wielding enemies.

Although I would rebutt that the most effective Antimagic Field is the ability to deal 200ish damage in one round (not that hard, even for a modestly optimized mid level build) and the Pierce Magical Concealment feat. A dead caster

[Hirax]

Although I would rebutt that the most effective Antimagic Field is the ability to deal 200ish damage in one round (not that hard, even for a modestly optimized mid level build) and the Pierce Magical Concealment feat. A dead caster

I've gotcha covered there. This is the build (http://brilliantgameologists.com/boards/index.php?topic=11867.0) I'm working on, which as both PMC, and the ability to do lots of damage, but not a ridiculous amount. Arguably. I posted it there to give another forum a try, just to explore the interweb some more, but I haven't got as much feedback as I'd like there, so I'm probably just going to post more questions about it piecemeal here.