[quote=@Shadow Dragon]
<Snipped quote by Legend>

Why not get them to destroy each other, then take out the last one when it's too tired to fight back? Then you'd have control over everything.
[/quote]

There are countless groups fighting for control, so it's not that simple. The one that's closest to winning full control is Signatrest, but even then, their forces are so widely spread that getting the last few percent is nigh impossible.