I tend to build my fortresses around large central shafts, and this time was no different. I breached an underground lake pretty soon, while delving for a granite layer to house my fallen. The shaft emerged in the roof of the cavern, with nothing underneath for many tiles but 7/7 water, so I shrugged and carried on digging a cistern. My military was strong, my stores were overflowing, and I needed to concentrate on providing for my dwarves. I assumed I could deal with anything that might fly up the shaft.
I was wrong. A year later this ...thing... turned up:
Quula flew straight up the central shaft and ploughed through my dining hall, killing over twenty dwarves. My military arrived shortly afterwards, but their weapons had no effect. After all, he was made of
salt. They all fell at his hands. I was about to abandon until I realised that salt -normal salt at least- is vulnerable to water. I formed a suicide squad out of the remaining dwarves and forced the invader into my farm cavern, then locked them in and opened the floodgate. My brave wrestlers were taken apart one by one by Quula as my last few remaining civilians walled them in, and their blood mixed with the slowly pooling water.
Eventually the cavern was fully sumberged. Quula stands unmoving in the center, having neither dissolved nor drowned. The twisted and broken survivors of the battle lie in the miasma-filled hospital cave, their wounds slowly festering, while my surgeon hunts vermin for food. Forty-seven dwarves in total have died by the beast's fists.