I decided to rig him up to a doomsday switch. I was digging deeply at the time and knew it was a matter of time since I was digging aggressively and had a small army. As it turns out a single beast from the candy depths crawled out of a crack in the rock and moved quickly, it scuttled through the mines and through a modest barracks, my dwarves were ill prepared and with the miners and soldiers dead, the lever was pulled. Ewiwi waited patiently on the surface, apparently enjoying the screams of his captors from below which lasted for some time. While poor on physical defence the fort was rich in terribly optimized pathways ensuring a slow and arduous escape for the monster below. Eventually the beast from below exited the fort, gave a gentlemanly nod to Ewiwi, and left east.