I'm doing a mini-project I like to call Dorf Abbey. I'm limiting myself to 40 dwarves, and all of them will be part of the military rotation.
I struck adamantine right before getting the military up. In an effort to get to the section of the tube above me, I built up stairs. Unbeknownst to me I had unwittingly built them into the cavern above me, allowing the two FBs to path right into my fortress. They immediately slaughter about 15 of my 50 dwarves, and another 5 as the Militia finally take them out. Then the tantrum spiral starts. Dwarves everywhere start tantruming, and then dying of poison, and then going beserk, killing their fellow dwarves, causing the sane ones to tantrum and killing more dwarves. Many go insane.
In the middle on the tantrum spiral one of my Dwarves goes Fell, and drags my legendary engraver into a butcher's shop. He creates a Dwarven Bone Mask.
After the carnage and the bodies have either been buried or dumped into the magma sea (15 dwarves left at this point, two unable to stand, three children, two insane) and the breach has been sealed, my leatherworker goes fey all of a sudden. He goes grabbing all sorts of things, and when he finally finishes I get:
The Fenced Miseries: A Forgotten Beast leather shield
It's encrusted with Black Diamond, and it's decorated with MORE forgotten beast leather. Two FB leathers in one artifact.
I definitely plan on having an adventurer come to claim those items. I'll call him Misery.