New defense building - siege tower

As mentioned above..it is a defense building..
(I didnt check before posting this..so sorry in advance)
And here is the catch.. This piece of building is a passive one unless activated by a troop running on the lever which can be set anywhere on the base.
It is upgradable to level 4.
Damage per second - 48 -> 58 -> 74-> 89
Hitpoints will be 400 -> 500 -> 600 -> 720
It can be built by dark elixir.
Cost is 18000.
Upgrades are worth 34000..47000 and 89000 respectively for every level..
The lever would occupy a 1x1 space so it would be very hard to identify..
The tower would be having a cannon in the middle firing bombs..
It can target only ground troops..and it has 1.5x damage for wizards.
Its range would be 9 tiles.
Please give ur feedbacks..
Supercell consider this..