Then why would they bring them?
I have a better theory. SHedim are actually controlled by someone else, a dark and evil person, much like we control the dwarves. But while we kill of random nobles who make requests, they kill of the peasants. Think about it, since Shedim nobles are usually higher ups, they can't kill them since they are worth to much. So logically they send them to a well defended fortress with a pack of betraying animals. Armok is then pleased for the lack of noble blood.
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A Shedim invasion attacked my fortress in the second year. I was of course expecting a few scouts, but I was not prepared for what did happen. A Shedim Ah tel showed up with a few ranged support units and the scouts I was expecting, which could have killed me if I was unlucky. I put my marksdwarves, brave and well armed, but green, on the hole leading to the rest of the fortress. They held there, shooting down several of the weaker enemies, but half of them got shot down by the enemies ranged units. They bravely held out while the enemy rushed toward the incomplete cage trap pit I was making. Fortunately the Ah tel was captured here. I now have a captured Ah tel, what do you guys think I should do with it?
No, I have two strong ones. A destroyer and a blade arm. I built a little Colosseum just for them, and hope to pit them against enemies I find in the future. The others I might just execute by firing squad to train the new troops, since all the old ones got wiped out. I am thinking hooking up the cage to a lever, putting it behind a fortification, and having my men take shots at it. I am just going to capture the enemies in the cage trap and throw them in with the stronger ones, still, of course. Personally I am hoping that I can capture some Shedim from a separate siege and have a clash of the titans, maybe a forgotten beast or something similar.
The destroyer got out, do to a mistake in my part in the Colosseum design, and set the fortress to evacuate so he could be captured again. One of my soldiers stayed back with a cougar that was being attacked, and shot him in the back breaking his spine. The cougar continued to attack, and while all it's attacks bounced off, the enemy died. Aww.
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Does anyone know how to get torchbearer gargoyles now? They are not at the shrine of victory, as the reference sheet says...