Just as the human caravan arrives for the first time, the Dark Stranglers are back. Not a problem in and of themselves. I've battled them in many embarks with various mods. However, this time they've brought an entire squad of eight war-trained magma hounds with them. Capable of breathing fire, and spitting fireballs. I don't *think* they're building destroyers, but I think I'd better not try to take pot shots at them from my guard tower. I don't think my puny defense force could handle getting set on fire just yet. Hopefully they'll go away if I kill enough of the stranglers. Going to be tricky.
Some other thoughts, as I'm slowly building more of Mastercraft's special buildings: The storage unit is set to unpack all crates automatically. That's not really something you'd expect from a storage facility (I spent quite a while trying to figure out where the crates I'd bought had vanished to!), and negates its potential to be a useful way to keep clutter and item count down until you truly need the gear. I've modded my version now to require record keeping instead of being automatic, to give my book-keeper/quartermaster something else to do.
Edit: The magma hounds did indeed leave after I sent a brave melee squad in bone gear out my back door to teach the stranglers a lesson. For a while, all was peace, then a night stallion flew down from nowhere and set everything on fire. It seems the universe had decided death by fire was going to be the final destination for some of my dwarves. Apparently everything I meet today is able to cast fireball. I'm sure there's a way to counter that, but I'm not sure what it is yet.