Pretty sure i already said this once before, but i had to re-start my game due to switching browsers, so it's fresh on my mind now.
More ability to interact with / utilize the Alarune and her effigies would be great. In particular I'm thinking of the ability to basically replace the Elves in the Wayfort (aside from some special cases like Daliza) with custom produced Effigies. We know the Elves are already stretched thin thanks to the events of Winter City, so giving them back some of their men could be good for them.
Way i see it, we could talk to the Alarune about maybe getting some custom Effigies to serve as the Wayfort's protectors and population. Maybe go on a quest or two that would allow her to produce more variety in her offspring (Maybe there's one breed of Effigie that requires something from the Behemoth, so people who spared him can get a little extra), and as a result you can now ask her to produce taller, more physically capable effigies.
Way i see it you could have a few possible choices on what you want populating your Wayfort.
-Taller, stronger, but less lust-inclined Effigies that can serve as your standard soldier / archer replacements
-Larger Bimbo-esque Effigies that aren't so physically inclined but can use lust and chemicals to incapacitate their foes
-Effigies that are slightly taller and slightly less sex-obsessed that can act as the civilians and crafters of the fort, making things like arrows and armour, etc.
-Normal effigies, idk.
Maybe you get to choose which one populates / guards your wayfort, maybe you get a mix of all the possible outcomes to fill the multiple different roles, idk. I'd probably want a mix of them myself, some more physically capable and less sex-crazed effigies to act as soldiers and guards, some crafters, a bimbo or two to act as a "therapist" or something, etc.
I just like the idea of having the option of having your own little personal army / population working for you if you decided to spare the Alarune, rather then working with borrowed Elves. You can already see the start of this when Farrah moves in, as it notes how the Effigies are helping to clean up the fort and build things for her. Think it's mentioned at least one more time too.
Mechanichally it probably wouldn't change too much? Most you might see is just the word "Elves" replaced by "Effigies" in a few places, and maybe one or two image replacements. But theme-wise it's a fun idea, i've always liked having my own personal or custom followers in fantasy games like this, rather then having them given to me or borrowed from someone else.