The second siege finally broke. Almost immediately, the human caravan showed up and the wagons bypassed my closed fort. Well, duh, merchants, you didn't give me time to open the gate! There's still some merchants with pack animals, and I'm hoping they have at least a little yarn, since someone's entered a fey mood and needs it (tons of silk and pig tail fiber cloth, but they always want yarn...)
Open the gate... immediate notification of another siege, even bigger than the last two. Some dwarves managed to make it out the gate, so now I have to wait for them to get back in before sealing it again. The goblins, lead by a (human?) lawgiver, slaughter the merchants and their animals, buying me some time. Still, a couple dwarves are caught outside when I seal the fort again. Population reduced to 90.
Some gobs are running into the serrated disks, but I wonder if I can clear some out faster. I pull the lever on my magma flood trap. The notification that I am under siege disappears pretty quickly after that. However, the dwarves take their sweet time pulling the lever *again* to cut the flow, so now I have more magma filling my entryway than I planned. Not a problem for the fort itself, but I can't export all this crap I'm making unless I can clear that path.
Side question, sparked by this event: it looks like the caged (mega)dragon that I haven't been able to pull inside yet was unharmed by the magma. There were a couple war cave dragons in the siege that were seriously burnt, but the megadragon doesn't show any wounds at all. Is this normal? Are the largest dragons immune to magma?