What are some cool builds for a duergar BBEG in 1e?

Need some that would work for level 4 to 6 characters. Anything from paizo is good. It'd be up against a party with a brawler, an alchemist, a rogue, a warpriest, and a cleric. I have a few duergar NPCs I've made but nothing too original for builds.

Sorry for the soijak but it looks like a duergar and it will attract attention to my post.