Can you help me design a group of Yuan-ti NPC's? (My players stay out)

[Psion]

Some of your CRs look a little high. Spellcaster levels < the creature's base CR only count half towards the creature's CR unless it has casting levels that it stacks with (like a Rakshasa).

 

[Brakkart]

Okay so with that in mind my 2 spellcasters are Hsss and Sssqueeze, so they now look like:

King Hsss: Halfblood Sorceror 14. CR 15

Sssqueeze: Halfblood Cleric 11. CR 12

As both cleric and sorceror are nonassociated classes, thus the first 7 levels (to equal their 7 base hit dice) only count as half (I rounded down) or 3 levels. This works out well, as I created a nifty staff for Hsss today and now that he is 14th level, he can actually have made it himself. so I'll add Craft Staff to his feats.