Clandestine Nation idea

[Metalder]

I'm trying to come up with a mod nation that relies heavily on stealth, dark magic, and assassinations, rather than direct combat. The idea would be some sort of sinister cabal that is trying to take over the world from behind the scenes, by means of bribery, spying, seduction, heresy, targeting killings, and of course, evil magic. The priests would be stealthy too.

I know that there are some units that may be good for some of these purposes already (assassin, spy, necromancer), but I will have to mod some in. I was thinking that there would be three levels of power ("circles" maybe?), corresponding to power and cost. Like, a first-circle (lowest) necromancer would have the generic powers of a vanilla unit, while the second tier would be able reanimate the dead as an option for a turn, and the third tier might have the ability to reanimate more powerful undead and possibly have some sorta magical ability as a standard attack. Likewise, the seduction units might just be something like a regular but very attractive woman, a sorceress with magical luring powers, and a "flightless succubus" sort of unit with magic.

So yes, it would have the generic mercenary units placed as recruitables, but be geared more towards stealth. Any ideas?