I'm conveniently located in the center of a ring of three dark goblin fortresses of different civilizations, so I'm expecting some intense goblin interest in my activities. I've already done the "overpowered weapon traps in front of a raised fortification in front of a bunch of overpowered marksdwarves" thing, so here's my more entertaining plan for dealing with sieges while I'm busy smelting iron to build my megaconstruction:
Goblins head for my bottleneck, and
1) Step on Pressure Plate A, which
2) Retracts the bridge at the same time that most of them are on it.
3) The goblins take some damage from falling two z-levels, and step on Pressure Plate B, which
4-i) Activates the many upright spear traps in the pit, each having just one, crappy quality spear. The goblins all take a little more damage, but ideally survive because Pressure Plate B also
4-ii) Activates the gear assembly between a waterwheel and pump tower on the other end of the map. When the water reaches the top of the tower, it activates Pressure Plate C, which
5-i) Opens the cages in the aforementioned pit containing a couple dozen war dogs and tamed cougars, alligators, etc. These creatures then annihilate the crippled goblins. Pressure Plate C also
5-ii) Deactivates the gear assembly connecting the waterwheel to the pump tower, and
5-iii) Opens a floodgate at the base of the pump tower to drain it.
(The reason for the pump tower is to act as a delay, to ensure that the animals are not released before the upright spear traps activate.)
Problems:
1) I have to recage all the animals, and reconnect all the cages to the pressure plate.
2) Will the spear traps and the bridge reset themselves once weight is off the pressure plates? If so, does this mean that the spear traps may trigger again while the animals and goblins are fighting? If not, how do I reset the traps and bridge? By using a separate lever?
3) The wiki says something about gear assemblies "toggling" differently than other devices - will this affect my intended trap-workings?
4) Anything else?
I know I should just make an automated drowning chamber, which is definitely pretty awesome and takes less time away from by iron-forging, but it seems so Dwarf Fortress-esque to kill your enemies with a combination of fall damage, trap damage, and ravenous beast damage. All because they stepped in the wrong place.