Funny story (for a Dwarven value of funny) While the Hill Titan was mopping the floor with his opponent, dead Doorf notifications started spamming. Some unknown was gong around unlocking the security doors in my fortress and had managed to set free two Forgotten Beasts that were trapped below. Luckily one was derping in a corner with some pathfinding issue, but the other, typically a web spitter, was tearing through my troop of miners. 20 dead before I even re positioned the camera! Time to send in some lucky soul to tether an alpaca down there!
Fantastic. I recommend setting up some big burrows differentiating surface, fort interior, and caverns. So when there's scary things in the deep you can set your entire fort to stay in the fort and surface burrows to prevent them from getting into mischief in the danger zones. Adjust as needed if there are scary things on the surface.