[JaydedOne]

Well, in terms of costing gems, troops, movements, etc., the commanders function pretty much as expected in that they're normal commanders who just sometimes decide to ignore your orders. They can gather up troops spawned by the Dominion effect and shuffle them around quite nicely. You just have to be prepared for them to potentially misbehave while helming such troops. While I haven't seen it myself, I'd think twice before entrusting my insane hybrid cultist with 50 or so mad deep ones in my capital or another significant province. After all, what if they randomize to pillage or decide to step next door into a vast enemy force?

But, given that they can develop priest and Astral 1 abilities as they gain more insanity, these guys -can- cast spells, forge magic items, etc.

There's an insanity score, btw. It generally starts low (many of my mad cultists start off at 7) but it goes up as time progresses (I've seen it at 50). Also, your normal commanders can go insane in time within your dominion as well, as some of my enslaved Atlantean magi began to wig out and do unscripted orders as well. I have no idea as to whether this can happen to your Pretender as my Void Lurker was happily Imprisoned throughout my entire playthrough -- which may be a strategic element to consider as well for R-Dreamlands, as you gain massive scales/Dominion plusses for Imprisonment while getting the side benefit of not scoring Insanity in the early game, assuming it applies to your Pretender...