Reply to above post is spoilered due to size of post.
Could you hypothetically lure a necromancer into a trap using dead bodies as bait?
It would have to be a big trap, or military Dwarves in ambush. But yes, you can, and it works with ambushing necros too.
(recommended doors as I'm not fully aware of how their raise dead works/range on it)
Works on a line of sight basis. Generally if you want to lure your necro away, you'll want the corpse items to be in line of sight (animal skins make good scapegoats). Which means you'll have to make the trap big, or have military Dwarves ready to chop some necro heads off.
Okay so (remove the doors?) and increase the length, and make the ramp come up underneath him so he falls down to that z-level. Should work now. I suppose just having the military dwarves pop up out next to him/them below where he ends up works, but I'd prefer to avoid any more dwarves than possible risking exposure to all the undead .
So I got bored and decided to build a ridiculously silly trap for catching this necromancer. I pretty much used this post as my note pad, so I've spoilered all the now-useless (or partly out-dated) information.
This spoilered bit is more notes I wrote to use for designing this trap, like the diagrams below I left it in as a ROUGH idea on how I set it up. Irrelevant now since I went and created it in the game itself, but should tell you what the symbols are if you don't use this texture pack. Go by the pictures I took instead of this information, it's "very outdated".
Alternatively, dig out a tunnel to 1 square in front of the necromancer, on the z level below the necromancer. Now build a door on the second last square (so like this: ------D-N), and dig a tunnel BELOW this tunnel. This tunnel needs to have the last spot TWO z levels below the necromancer himself. Now dig out a + shaped room with the necromancer being in the middle (two z-layers above), and build a support on that middle square Now build a statue on the tile opposite the tunnel, and the two flat sides above and below (or left and right depending on orientation. Return to the first tunnel with the door. What you want to do is dig out a 3x3 room like below, except leave the necromancer tile in the middle untouched. channel out the horizontal and vertical (not diagonal) tiles so that the centre tile is supported fully by the support only.
First trial of idea, left it in just in case it could be useful somehow. (End result of mine makes this outdated though)
Ideally it should look like this:
Legend:
D= Door
N= Necromancer
-= Tunnel
S= Support
s= Statue
h= Channel
T= tile directly below necromancer (supported by the support)
`= Nothing, just to try help with aligning the pictures
Surface N
First tunnel (z1)`------------D-T
s
second tunnel ----------------sSs
s
Rest of the work should be evident in the screenshots I'm posting, I've written this out half for my own benefit while coming up with it (Haven't worked out how to prevent the dwarf ending up in the trap as well unless he is fast enough, maybe if you pause-unpause constantly? Might not be worth risk, get a useless guy to do it)
Here are screen shots of it (generated a fresh world to demonstrate it):
Surface (necromancer's square would be on the tile that has been channeled out and shows as the brown downwards triangle in the obviously mined out square)
Level directly below necromancer (the upward triangle is directly below the necromancer's original location, and is what it should look like after you have built the ramp under his feet. Obviously it's empty at this point.)
Next level down ( the I is the support, and I've built walls in the spaces between the statues)
The end result is that you have a necromancer confined in a 1x1 square with easily removable statues blocking him. Cage traps mean that you can safely dig the ramp beneath the necromancer without risking a security breach, and if he steps on those then there's no problem. Door setup means if zombies do follow you down, you can just lock one to prevent them getting further in before you manage to get a wall up. Burrow the miner on one of the cage traps, then lock the door behind him. Multiple door setups mean that in the worst case scenario, you can lock the necromancer in the tunnel and fill him with bolts, although since they don't have trap avoid I don't see him getting out of the cage trap area any time soon. Regardless, an execution chamber exists with fortifications for marksdwarves and you could also put a bridge between the doors linked to a lever if you wish, then you could just set the bridge to raise/lower repeatedly and kill anything that steps onto it (but we don't want to lose our dear necromancer so easily do we?)
As I've said above, the device is currently shown as if you had dug beneath the necromancer already, but not set off the small-scale cave in which would deposit the necromancer neatly trapped in the 1x1 statue room. Yes, I'm aware this is idiotically over-complicated and only works on a target that stands still. That's the point. The bigger and more pointless it is, the more satisfying it is when it works =) Ideally the necromancer should be standing still since he has nowhere to path, and you will have waited until he finished raising any corpses in the area. Best part of this is you can set it up without any access to the outside world (the whole point of it to be honest), and please don't point it out, I'm aware that the layer with the traps looks like a giant key =P. Funny how things turn out sometimes, considering this is to lock up a necromancer aha.
Last but not least, good night. I have to get up in four hours roughly (curse my curiosity regarding this device!) so I'll probably reply in the morning at some point. Might put this in it's own thread if it is amusing enough, I don't know. I just find the idea of caving in the ground beneath his (the necromancers) feet like this hilarious.