By the power of Evil

[WarlockLord]

So I have a wizard/anima mage with the Aligned Spellcaster ACF from Dragon Magazine that turns all his spells evil. 

I have the feats Spell Focus: Evil, Greater Spell Focus: Evil, and Malign Spell Focus.  I am planning to take Fiendish Power from Complete Mage, after taking Fiendish Heritage.

Are there any other feats that increase evil spell dcs?  Thanks in advance.

P.S.  No, we are not using taint, don't even think about it.

[Nunkuruji]

Planar Touchstone (Evil Domain), for caster level

I think that's about it for DCs

[ZhonLord]

I don't know any other feats that increase evil spell DC's, but you can always take advantage of the Violate Spell feat from Book of Vile Darkness.  Your spells already have the evil descriptor, but you'd still get the benefit of having half the spell's damage be dealt as Vile damage, which there is no resistance against and can only be restored in a consecrated or hallowed area - great for countering enemy healers and energy protection spells alike.

The feat only modifies a single spell as written, but since BoVD was written for 3.0 I'm sure your DM would allow you to treat it as a normal metamagic feat if you're playing 3.5 - and only a +1 to the required spell slot makes it useful for the vast majority of damage-dealing spells.

[ariasderros]

Well, there's the obvious point about raising your Int to raise the spell DC's, which has the added boost of the rest of what that goes toward. (Bonus spells, skill points, your relevant skill checks)

But since you are only asking about raising the [Evil] spell save DC's because all of your spells are [Evil], I have to default to the other things people usually do to raise their spell DC's.

Which brings me to the next overly-common point: Eschew Materials + Snowcasting + Cold Spell Focus + Greater Cold Spell Focus + Draconic Aura (Cold).

[awaken_D_M_golem]

If you worship (wtf) an Elder Evil you can get
5 bonus feats on a schedule.  iirc they are [Vile].
Fits with what you're doing.