Ok so I've been playing DF for a few months now and I finally have a fort that isn't being dragged into hell by the FPS monster and it's a site that has exactly what I want. Now as far as my experience with sieges goes, I have only encountered one, and that was by humans who were attacking me for reasons I don't know (I had the orc mod at the time and I can only assume a human got caught in an atom smasher during an attack).
Anyways I'm planning on creating a long maze-like hallway for sieging gobbos to meander through as they have their eyes gouged and fingers torn off by a random assortment of crappy weapon traps. But I've envisioned a final coup de grace that will finish the entire lot of them off: The maze/long hall will end at the widest z-level of my bottomless pit, where the goblins find themselves having to cross an incredibly long bridge/walkway (haven't decided on how I want to span the pit yet). Basically the idea I have is that once all or the majority of the attackers are on the walkway, a massive cistern will flood them off of the walkway from the north side and into a pit of upright spike traps. Here is where I have some questions:
1) I really want the flooding to be like a tidal wave that almost instantly blows them off the bridge. I'm not too sure how to accomplish that though, should I:
-Use screw pumps en masse
-Set up the cistern almost directly above the bridge and use some sort of hatch/floodgate system to just drop all the water at once (not sure if that is even possible but I feel like it is).
2) I realize that the spike traps themselves may not actually finish them off, although that would really be just a matter of putting in more preliminary traps to soften them up some more, but I would really like the spike pit to be the finale. Does fall damage still come into play when landing on spike traps, and if so, how many z-levels down would you suggest I actually set up the spike pit?
This is my first attempt at any sort of major trap project and I would like it to turn out well, so any suggestions and/or feedback would be greatly appreciated.