I just think it would be cool to fight an epic battle in a place you've become intimately familiar with over the years. It could be a cool final culmination of the story. The idea admittedly came to me from memories of FFXI. In Dynamis, you fight in an alternate, future? version of the hub towns after they've been conquered by the beastmen. It's really striking how a zone that you'd associated with peace and safety since Level 1, has now become a place of danger (enemies will kill you instantly). I think there's something cool about revisiting the same space in a different time period because it can invoke some powerful emotions. The Pillar of Autumn is revisited in Halo 1 too after it has been reduced to a desolate, burned out shell. It was a great way to end Halo 1 (along with the Warthog run) since it brought everything full circle. Btw, I just changed my mind. The raid should start at the bottom of the tower, and you'd work your way up to the very top for the final battle. Combat wise, I think it could work. The damage to the tower could reshape the map geometry (destroying walls, adding rubble for cover etc.) to make it more fitting for a boss encounter.