Frontier Left-Sloping Inverted Wall

Description
Walls are a comfort for the timid, a strength to the strategist and a trap for the unwary. A barrier against the savage world, walls can be built as high as the stability of the foundations will allow. The strength of the materials used in their construction will determine how long they stay up. Just remember to add a door. Weapons barely chip it and even explosive powder is not enough to weaken it in a single blow. Siege weapons or divine intervention are really the only way to bring down walls this strong.

Repair
Repairing  requires up to:
 * 7
 * 3
 * 2