How about new build like
Cost:
3000x Any Stone
1000x Dry Board
20x Glass Pane
10x Wrought Iron Bar
4x Blistersteel Bar
2x Arcane Amethyst
Size: 10x10
Floor 1st: Size 15x15
Floor 2nd: Size 15x15
3rd: Size 15x15
4th: Size 15x15
5th: Size 20x20
6th: Size 30x30
What to do ? Nothing
or
(optional proposal) work like Big Blazer - with range 300x300 and defense area
Ammo: cannonballs