40d:Fortress defense

Entrance traps

Flooded Entrance

Using a chamber as your entrance alongside a chamber full of water and some machinery you can flood or drain the entrance at will.

The basic premise requires two levers, two screw pumps and two gear assemblies. The amount of power required and the number of additional components needed to get the power to the screw pumps varies depending on distance/setup. One pump is placed to draw from chamber 1 and dump into chamber 2. The other is set in reverse. A gear assembly is placed next to each pump and connected to the main power system. Each gear is linked to a lever. Now at the flip of a switch you can submerge your entrance with water or magma for easy, secure defense against creatures that aren't amphibious or magma-dwelling, depending.

The picture above shows the design in action. The green pump is currently on while the red has been disconnected through the grey marked axle. The yellow X is just to mark that there is a channel under the axle.

Siege weapons

One effective way to have seige weapons defend your fortress is:

• . - floor
• # - wall
• s - ballista
• > - Stair
• - channel

        ###########################sss
Entrance...............>     sss...sss
Entrance...............>     sssssssss
Entrance...............>     ssssss...
        ########################sss###

Using this design you can cripple an army using a well timed volley (well once armies actually attack you will)

Siege engine