Regarding earlier requests for clarification concerning my "Siege Tower" piece...
The siege tower is a single unit composed of two segments, one stacked on top of the other. Being a single unit, both segments move at the same time. The idea behind the siege tower was to make, essentially, a tougher rook. It must be "captured twice" in order to be removed from the board, one piece per segment. When an enemy piece captures the siege tower, it is removed from the board just as if it were traded for a piece of equal "hit points". This simply means that it will cost one player two normal pieces to remove one hostile siege tower from the board. If one's own siege tower were to attack the opponent's siege tower, the attacked tower is then dealt basically "double damage" and is completely removed from the board (this must be so since two pieces cannot occupy one square).
I hope this helps establish some clarity. If I must elaborate more, you need only say so.
Probably worth slightly less than 7 points. Close enough.