So I have just caught two necromancers. What to do with them ? Kill them for revenge ? I've got a better idea.
Necromancers cannot die of old age, do not need food and drink and will reanimate pretty much everything they see, except when in cages.
Well, here's what you can do, for infinite training possibility for your military, and amusement for the dwarves !
Carve a large room, that will be your arena. Possibly with chairs and an amphitheater/theater on top, for Roman goodness.
On one side of the arena, make a 1xX line of empty blocks for the necromancer's prison, carve fortifications (so the necros can see the arena) and drop your caught necromancers in there. Optional : Make a few bridges lifting towards the fortifications, and activated by levers, as a makeshift curtain. So the necros can see the arena and reanimate things inside it only when needed.
As a plan :
WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW
W Necromancer's Lair W
WFFFFFFFFFFFFFFFFFFFFFFFFFFFFF W <= fortifications
WBBBBBBBBBBBBBBBBBBBBBBBBBBBBB W <= bridges, retracting upwards here and all linked to a lever
W W
W W
W W
W Arena W
W W
W W
W W
W W
WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW <= walls, of course
Of course, make entries in the arena, make sure the necros can't get out and can't see any unwanted corpses, and armor your dwarves well because this is a real fight, and your dwarves might die. Make sure the dwarves can't kill the necros as well (marksdwarves).
PROS:
-Infinite training
-Fun for your dwarves (notably killing zombies)
-Faster than military training
-no need to catch more gobbos to feed your military
-easy to use, on/off reanimation lever
-Amusing
-Probably easier to do than a giant sponge training dummy
-Difficulty level customizable.
-Can even train marksdwarves with proper care
CONS:
-Actually can be dangerous for your unskilled/unarmored military
-Necros can get killed if you don't pay attention
-Untested yet :p