I've tried this, really I'm the guy who wanted to be a swarm, before on the old wizards boards my builds didn't come up for much but I'm trying to help instead of lurking. I'm actually just listing cool things I've found that might help you out. There things I would have tried if making a deity again, I wouldn't have done illithid savant, but fiendish illumian with some of these tricks, It's kinda mean but I think you are unto a similar idea to where I quit. Also part of the problem is you'll run into so many ways to run things more efficiently that it might unmake builds, which happened to me several times.
I see a distinct lack of Palladin especially since prestige palladin was allowed, can't you use warmage/beguiler as the base for casting, you can grab battle blessing and sword of the arcane order along with rainbow savant. This gives you three SDA's kinda + turning and divine grace.
You also don't seem to have vow of poverty. I think you can use that and sacrament of true faith from grey guard and kinda just ignore the hole poverty part of the poverty.
Fiendish is a good template since ravages were allowed by Tshern.
http://dicefreaks.superforums.org/viewtopic.php?f=12&t=78 I mean they are very good, and since you probably don't want the level adjustment to get virtual class level the only other way to get them seems to be eating the brain of a Demon Lord. They get 1d6 from the template as one ability, I think this should save you your Factotum levels, also this is better than the Monster of legend template.
http://dicefreaks.superforums.org/viewtopic.php?f=12&t=78*disclaimer did not check this part
Also good to eat there spell like abilities because they can grab psionic spell likes to grab bend reality*
Greater arcane fusion is good at will too I think this can be done with feats, along with limited wish.
If possible I'd pump these spell like abilities with my SDA's instead of spells since they would be at will, twin and quicken. I don't see a caster level trick in your build, I think you should add warlock invocations and master spelltheif.
Your ability scores seem low especially constitution, have you considered mind switching into a creature optimized for physical stats, like a legendary war troll wear-dire tortoise?
I'm not done offering suggestions I just got tired of typing, will add more later.
