Since captured beasties that shoot stuff no lnger need a path to target and fire, we can now build turrets quite easily.
Here's some designs I came up with:
"grilled wraps" (needs lever operator to 'arm' and 'fire')
W W D (artefact) door, locked
W W . floor
WWWBB.....bbWWW W wall
W.=BB.....bb=.W B bridge, raises to the west. Lower this bridge to arm the trap (webs). Raise before firing to avoid killing GCS.
DS=BB..c..bb=iD b bridge, raises to the east. Lower this bridge to fire the trap
W.=BB.....bb=.W S Giant Cave Spider
WWWBB.....bbWWW c chain, with puppy or similar bait for the GCS to fire at
W W = fortifications
W W i Fire Imp, or other fire shooting beastie
"improved grilled wraps (only needs lever operator to completly shut it down, works automatically if turned on)
W W D (artefact) door, locked
W W . floor
WWWBB.....bbWWW W wall
W.=BB.....bb=.W B bridge, raises to the west.
DC=BB.....bb=dD b bridge, raises to the east.
W.=BB.....bb=.W C Webbing clown
WWWBB.....bbWWW d dragon
W W = fortifications
W W
in this second design, the clown's webs are fireproof, the clown can't be hurt by dragonfire, and the dragon will not mind being webbed too much. So you can have both bridges open at once. Needs testing to see if the clown has enough range to be able to target the dragon. If not, it still would start webbing as soon as enemies walk through the trap passage.