The Song of the Sirens. A maneuver brought about by sheer desperation. My girls created it to make as much money as possible for my Seeker War. By linking all 28 zones together, we were able to maximize our killing potential.
Instead of going after each zone, we took on entire floors. The gains we made were so great that much of Hellsend decided to ascend to Phantoms right then and there. And while it didn't end up helping as much as the Sirens intended, it was one of the cards we had to play.
The problem with defending such a large area came down to numbers. Numbers would determine how many defenders you had. And the number of invaders you had to defeat. You could supplement that with forts, but the numbers game didn't go away, it just shifted.