Help with NPC build

[Helmed]

Human.
Starting stats are all 18.
Class: Warlock 10 / Acolyte of the Skin 10.

I'm using a homebrew world based loosely around Greyhawk. The NPC will be roughly equivalent to Iuz; not a deity, but the ruler of a monstrous nation (who acts as "Iuz-like" as possible given the lack of divinity). I want to keep the entire Acolyte of the Skin progression but I'm open to suggestions on the warlock progression (Should it be wizard instead?).

 

[Rystil Arden]

Human.
Starting stats are all 18.
Class: Warlock 10 / Acolyte of the Skin 10.

I'm using a homebrew world based loosely around Greyhawk. The NPC will be roughly equivalent to Iuz; not a deity, but the ruler of a monstrous nation (who acts as "Iuz-like" as possible given the lack of divinity). I want to keep the entire Acolyte of the Skin progression but I'm open to suggestions on the warlock progression (Should it be wizard instead?).

If he's going to be an NPC rather than a PC, why not just make him a Half-Fiend Warlock17? Better powers, less caster level loss for the CR.

 

[Helmed]

Sorry, prolly should have mentioned:
Houserule: No Half-fiends, Half-celestials, Half-dragons, or Half-orcs; I barely let in half-elves.

Thanks for the quick reply.

 

[Rystil Arden]

Sorry, prolly should have mentioned:
Houserule: No Half-fiends, Half-celestials, Half-dragons, or Half-orcs; I barely let in half-elves.

Thanks for the quick reply.

How about Fiendish template then? It could be Fiendish Warlock18. The Acolyte of the Skin class is very weak for its Challenge Rating because it was designed to compensate for the ECL of some of the Half-Fiendlike abilities for a PC, rather than the CR for an NPC (similarly to Dragon Disciple for Half-Dragon). Particularly of note is that a Warlock10/Acolyte10 does not receive even a single Dark Invocation, for instance.