So like the fort resets back to default after a period of time giving every guild an opportunity to reclaim/take over the fort? Sounds interesting. But I think the power up ability/upgrade defense thing is a little too Balloon Battle or whatever.

I had this idea where the tower would have separate spawn points in the form of flags. These flags would be conquerable like the normal flags, but with less health. Each flag acts as a spawn point. Any guild is able to capture a spawn point, including attackers. However, you may capture as many spawn points as you like, but it's the main flag that really matters. Why would this be useful? Because it adds more stratiegics into towering. So say an attacking guild captures a spawn point. They no longer are warped out when they die or have to spend time regrouping. They can just pick up from there. The spawn points also work with the defending guild. They will be spawned randomly to any of the flags they own. Now defenders won't always be clattering over the door 24/7 because they have other flags to look after as well. If a guild attacking or defending has no spawn points, they will spawn outside the tower as normal. Having them will make conquering or defending much easier for the guild, and there wouldn't be too big of a "blocking" issue because attackers and defenders will be spread out over the tower.