In the latest fort that I've been running where I'm trying to get it to grown naturally from 20 dwarves, had the most annoying forgotten beast to date: a winged toad with a poisonous bite and warty skin[or sting can't recall].
This is not that difficult of a forgotten beast and the containment measures worked (double bridges were closed so the thing was trapped). The problem is that I spent the good part of a year in-game shooting it with a combination of bone (yeah, I know) and iron bolts and it showed no signs of dying
So I decided to get a bit more creative. A long trained giant cave spider was released into the archer gallery to spray the annoying pest with webs since the flooring was covered with cage traps; easy capture right? Except the pest was not moving and despite the prodigious webs everywhere, none of the traps were activating.
Okay, fine. I'll open the bridges and then it'll move, get stuck and promptly caught, right? No :/ The pest refused to budge until a dwarf accidentally open the door he was sitting in front of. The dwarf survived but the door was now stuck open (dropped item) and the pest was in no hurry to move. At some point another dwarf tried to get past to do god knows what, got attacked and promptly got themselves caged. Not too bad, since nobodies died yet (leads to an inevitable boatload of caged dwarves, but that's an aside). Containment fails as the pest finally decides to move around, and somehow avoids getting caged. Time for the close quarters military right?
Except this is DF remember, and getting squads to move exactly where you want them to is not easy. One of my spearmasters gets ahead of everyone of goes charging (without orders) into the bolt covered pest .... and promptly starts bashing it with his shield and kicking it. Despite being equipped with a spear and trained with it, the dwarf in question decided his best weapon was his natural weapons (he actually bit the pest o.O ) and his shield. Despite lasting much longer than I thought he would, he still ultimately took a hit to his head that crushed it despite his steel helm. In that time, the rest of the militia was busy gathering provisions and sleep for the long run down the stairs to the location.
The pest got itself cornered in a side room and hunkered down. After months of trying to gather enough of the militia in one spot for an assault, I got tired and order the two dwarves who were there to attack: one promptly walked off to gather provisions again and the other one crawled his way towards his foe. Yes, the one dwarf who decided he was ready to fight had lost the ability to stand from a previous military mishap. Said dwarf crawled his way to the beast and successfully stabbed the thing to death. He promptly named his spear. -_- When the cripple is smarter and fights better than your uninjured compartiots, you know you have a problem.