Mt idea is, while on lockdown, have areas close to the various entryways set up to fall in on themselves. Supports will lure trolls right?
I don't think so, no, but pressure plates trigger them, if I understand right. If you only want to kill trolls, it wouldn't be too hard to set up something like this with a lot of flooring above it:
# = pressure plate, can't remember the actual ASCII off the top of my head
S = Statue, as I don't know how to place the omega symbol
####
#IS#
####
Somebody steps on the pressure plate, it all comes crashing down. Granted, it wouldn't do much good, as the goblins themselves wouldn't approach it. HOWEVER... If you did this:
S = rope, can't remember that one either for some reason, either
E = giant emu
#######
# #
#I SE #
# #
#######
THEN we'd have something useful. Unfortunately, that's quite a lot of pressure plates... And a pretty good deal of mechanisms and linking. But...
W = wall, because I'm lazy.
WWWWWWWWWWW
W # W
W # W
W ISE #
W # W
W # W
WWWWWWWWWWW
That would keep there from being too many pressure plates, though it wouldn't destroy much,
unless the support had a wall built on top of it with floors surrounding it in a large box pattern surrounding a huge area,
basically:
+++++
+ +
++W +
+ +
+++++
except a lot bigger,
and the ground was hollowed out beneath it. You have a one-shot trap that would cave in an absolutely huge amount of land. Very,
very useful for mass sieges... though if it was spawn, it wouldn't actually kill (unless it was a very, very far drop). But then you have a huge area underground that would be completely worthless before and after, and would require a lot of digging. But it could potentially save the fort... if executed properly. If you made the bait only accessible by a raising bridge, which you could lower at will, you could choose which siege you wanted to destroy. But I'm not going to draw that out here.