Caution, concept spoiler
Originally Posted by The Vorpal Tribble
Illumian (Aeshkrau) Bard3/Spellthief3/GSA4/SubCh2/Unseen Seer 2/GSA 6 was the original build. Pump Strength, to get bonus spells from Aeshkrau and improve melee presence. Qualify for sublime chord using spellthief Steal Spell, and/or drakehelms with Versatile Spellcaster. From there, persist caster-level uncapped and relevant buffs using Practical Metamagic and your wealth of high level slots, like Cloud of Knives, Hunter's Eye (from Unseen Seer), etc. Use Drakehelms to get spells that would otherwise cost you a sublime chord slot (Cloud of Knives, Steeldance) The trick is in interaction between Master Spellthief and Sublime Chord, which results in a caster level of 45 at the 20'th level of the build. This makes an excellent skillmonkey as well, with Improvisation from Bard levels. From there, you could strip spells and buffs with impunity, having 3 free attacks per round and 8'th level spells (Arcane Spellsurge, if you wanted to hit more in melee)
After I realized that Steal Spell Effect didn't work if you weren't straight spellthief, though, I figured the other two levels of spellthief redundant, so perhaps I should change the build, to perhaps Bard6/Spellthief1/GSA3/SubCh2/Unseen Seer 2/GSA 6, which also had a less dicey SubCh entry, but at that point, the amount of rewriting and revision, since I just noticed it this morning, was far too much.