I'm taking another shot at this, I'm going to provide two builds, one for a Gnome and one for a Human using the shadowcraft mage adaptation. First the Gnome.
Gnome (with 2 flaws)
Gnome Illusionist 1/Illusionist +2/Master Specialist 4/Shadowcraft Mage 3/Incarnate 1/Soulcaster 1/Swordsage 1/Soulcaster +6/Fate Spinner 2
ACFs:
1) Specialist Wizard: Illusionist - Banned schools: Enchantment, Evocation (Possibly conjuration instead of enchantment?)
2) Gnome Illusionist (RoS) - Conjuration at -1 caster level (This stings, but we can mimic this later with Shadow Conjuration)
3) Chains of Disbelief (UA) - Lose Familiar
4) Illusion Mastery (UA) - Lose bonus spells per day from specialization, Substitutes for Spell Mastery requirement.
Feats:
1) Spell Focus: Illusion, Shape Soul meld: Illusion Veil, Heighten Spell, Improved Initiative
3) Signature Spell
6) Earth Sense
7) Greater Spell Focus
9) Incarnum Spellshaping
12) Earth Spell
15) Shadow Trickster
18) *Tattoo Focus
*There are two versions of this feat, the one in the Player's Guide to Faerun has a racial requirement while the one in the Dungeon Master's Handbook under the Red Wizard entry does not. This character has taken the DMG's version.
Spell DC's: 10 + 12 (int) + 1 (Racial) + 1 (illusion veil) + 2 (Soulcaster) +2 (Spell Focus) + 2 (Minor Spell Esoteria) +2 (Shadow Trickster) + 1 (Tattoo Focus) +2 (Spin Fate) + spell level = 35 + spell Level = 35~44 DC.
A pretty good DC, but it doesn't feel all that optimal. We lose 2 levels of casting in order to qualify for all our feats and PrCs.
True Neutral Silverbrow Human (w/ 2 Flaws)
Illusionist 3/Master Specialist 4/*Shadowcraft Mage 3/Incarnate 1/Soulcaster 1/Swordsage 1/Soulcaster +6/Fate Spinner 2
ACF:
1) Specialist Wizard: Illusionist - Banned schools: Enchantment, Evocation (Possibly conjuration instead of enchantment?)
2) Chains of Disbelief (UA) - Lose Familiar
3) Illusion Mastery (UA) - Lose bonus spells per day from specialization, Substitutes for Spell Mastery requirement.
4) *Shadowcraft Mage Adaptation
*The Adaptation for Shadowcraft Mages is this:
Adaptation: A cabal of nongnome illusionists could certainly use this prestige class; simply replace the racial requirement with a requirement that shadowcraft mages be members of the cabal. the requirement for a 4th level spell from the shadow subschool restricts this class to arcane spellcasters. If not for that requirement, clerics with the Trickery domain could qualify more easily than wizards or sorcerers.
Feats:
1) Spell Focus: Illusion, Heighten Spell, Tattoo Focus, Shape Soul Meld: Illusion Veil, Improved Initiative
3) Snowcasting
6) Earth Sense
9) Incarnum Spellshaping
12) Draconic Aura
15) Cold Focus Shadow Trickster
18) Greater Cold Focus Cold Focus
DC: 10 + 12 (int) + 5 (illusion veil) + 2 (Soulcaster) +2 (Spell Focus) + 2 (Minor Spell Esoteria) +2 (Shadow Trickster) + 1 (Tattoo Focus) +2 (Spin Fate) + 4 (Aura) + 2 (Cold Focus ) + spell level = 44 + spell Level = 44~53 DC.
DC: 10 + 12 (int) + 1 (Illusion veil) + 2 (Soul caster) + 2 (Spell Focus) + 2 (Minor Spell Esoteria) + 2(Shadow Trickster) + 1 (Tattoo Focus) + 2(Spin Fate) + 4 (Aura) + 1 (Cold Focus) + spell level = 39 + spell level = 39~48 DC
Using Silverbrow Humans nets a higher DC, but it involves a somewhat questionable adaptation of the Shadowcraft Mage PrC. Both characters use the same class build, but a different feat build. I focused on trying to get DCs as high as possible and to be honest, the character feels the worse for it. Anyone else have any ideas on how to do this?