Thousand Sons
Well, here's your first problem.
Aside from that, the thing that you need to remember with sons is that your only useful models are the sorcerers. Given that, making one of them a demonhost is not such a hot idea in my oppinion.
There are two commandments of sons list building:
thou shalt take and protect sorcerers
thou shalt take advantage of 2 wound terminators which just don't die.
Also, there's going to be a new chaos dex out in the fall, so don't buy anything before it's out.
cheers