So I'm running a game that has just started, and all is well. And I have a question of sorts in mind that I would like the thoughts of others on.
To preface the character which I will describe is not really an enemy of the PC's and it is unlikely that he will ever be. Nor will he ever be really an Ally, and as Such I will probably never stat him. Still...
So the empire that the PC's are in is a very racist empire, where humans are supreme, I won't go into details but there are very good plot reasons why this is so. The empire has endured for a thousand years (nearly) and is ruled over by the emperor a single individual, a mortal who obtained immortality, and great power. Anyways the dude is a lvl 30 Human who is a wizard based spellcaster, and his first 20 levels are wizard. Regardless of where he started out he is now most likely LE, and that in the least evil way, he is certainly evil, but he doesn't really wish people ill, he just got tired along the way and found that he just couldn't be kind or tolerant in any capacity anymore. You cause him problems? You die. Simple as that. He has been fighting another individual that takes people over like the borg but much more subtle this entire time, and this is part of why he is just so tired.
Anyways now that you have a better idea of who he is and what his personality is like, I'm thinking that I would like to have him take a prestige class for levels 21-30. What would be a sensible choice for such a person. Also he is a bog standard generalist, and not overly interested in necromancy (though he knows every last wizard spell in the books and a few more besides). My point is that he wouldn't take a prestige class based around necromancy.
Loremaster?
Why are you making him 30th level? Taking an additional 10 levels is not really going to increase his power as much as you think. There are no spells more powerful than 9th level so his magic power will not increase a lot even if his caster level goes up. The game system is not really designed to go over 20th level anyways.
A better way to increase his power would be to use the mythic rules. A 20th level wizard with 10 mythic tiers is way more powerful than a 30th level character. Mythic spells are a lot more powerful than normal spells. For example the mythic version of sleep affects all living targets that have 8 or fewer HD within a 1 mile radius at tier 8.
Well, if he is lvl 30 by CORE rules he gets 14th level spell slots. That's pretty nice. As for why not mythic? Because: one I don't want him to have certain narrative options such as mythic spells, and 2 because I'm not making this a mythic game so I don't want to accidentally let it slip that he is mythic and then everyone at the table thinks they are getting tiers.
As for loremaster, if I can't think of anything better than yes, but I'd prefer something more.
Another reason why lvl 30 is that way his simulacrum are much stronger (8th level spells)
What if he is "only" 20th level but has used the time and money available to fully maximize his potential. So he has used retraining rules to maximize his hp, wears a maxed out custom magic item in every slot, has 32 ioun stones circling his head, used wishes to get the limit on inherent bonuses to each stat, every spell eligible for permanency on himself, and has 8 adamintium golem bodygaurds. Does he need to be more powerful than this?
Edit: and several bound outsiders, a group of human gaurds/apprentices etc.. of 15th level or so, an artifact or three, a custom spell for just the occasion, and centuries of contingency plans.
Well, I guess he doesn't need to be level 30, but I dunno, I mean I assume he already has the things that Java man mentioned.
The main issue that comes to mind with a level 30 character is that you can forget doing social combat against them, just forget it. So maybe level 20 and call it a day? It just seems to lack something, whatever maybe lvl 22 just so I feel better about it or a couple of mythic tiers or something. I dunno.