| Take the heritage feat chain.
If non-evil go with fey chain, if evil go with fiendish.
The +1 to CL for Invocations is really handy against SL.
I am running a sorcerer/warlock with the fey chain and his Hideous Laughter spell is truely awsome. Fey Power (prerequisite Fey Heritage) gets you +1 CL with Enchantment spells in addition to the +1 for invocations.
I also picked up Fey skin at 3rd level (DR is always a nice thing to have).
Chose not go with "blaster type" due to setting and went with See the Unseen. | 
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