I feel like my theory is being pushed a little bit to the side in terms of what I'm actually trying to say.
I'm not saying the Void is taking sides.
I never said the Void's goal is to empower one city-state.
What I'm saying is that they're using the already present situation of the City-States in order to create a distraction, or in-fact start a War.
Demacia and Noxus hate eachother. Fact
This most recent even could lead to a war. Fact
If there is a war, there will be many MANY casualties. Fact
After (if there is) the war, both sides will be severly crippled, all of RuneTerra would be in chaos. Fact
If all this were to go through, the Void could show up, be like -Hey Guys, how's it going?- And wipe everybody out.
I'm not trying to force it, I'm thinking outside the box. All my points are completely valid.
I doubt the Void is just being a sub-plot through all of this. You yourself just said Larkhill, Cho'Gath is the equivalent of Swain in the grand scheme of things, a master tactician, and a general. And yes, he is waiting for Malzahar's plan to go through. Obviously they're having some problems, but it's only Kassadin. They're being in the background is the point. If you're trying to destroy the world, then why not pit two city-states who already hate each other against each other to do it for you?
Swain and LeBlanc have been working in the shadows for quite some time, and this has been their goal all along.
But it just seems...to easy.
The only reason Swain has his position is because General DuCouteau went -poof- after some very agitated actions. I do not, however, believe it is within the capability of Swain to destroy not only Darkwill, but the entire squad that was with him. True, things do point to it, because of the -no signs of a struggle / retreat / whatever, but it just doesn't sit right with me.
During Swain's time in Kalamda they were keeping eyes on him, and it was said he was constantly wandering the out-skirts of town, but never leaving. It's in my opinion he knew something was out there, or something was going to happen.
I don't think he wandered out of town, approached the squad, and killed them all in an instant. Swain might be powerful, but not that powerful.