Let's see if I remember my build...Focused Specialist Illusionist 5 / Incantatrix 2 / Shadowcraft Mage 5 / Incantatrix +8

Feats:
1 Iron Will
3 Spell Focus (Illusion)
5 Heighten Spell
6 Earth Sense
6 <open metamagic>
9 Earth Spell
12 Easy Metamagic (Heighten Spell)
14 <open metamagic>
15 Residual Magic
17 <open metamagic>
18 Arcane Thesis (Silent Image)
20 <open metamagic>

Earth Spell and Easy Metamagic let you heighten Silent Image to a 10th level spell (for 9th level shadow spells) in an 8th level slot. Residual Magic lets you do it again next round in a 1st level slot (or 0, if you take the racial substitution level). You have four extra metamagic feats to play around with, all of which can be reduced by 1 by Arcane Thesis. If your DM allows it, I suggest taking a flaw for Arcane Disciple, for spontaneous Miracle or similar cheese. Alternately, two flaws for Spell Mastery and Signature Spell (Silent Image) give you serious spontaneity.

On the downside, you eventually have four prohibited schools (left with Abjuration, Divination, Illusion, and I recommend Transmutation), although Evocation and some of Conjuration can be compensated for through shadow spells.