Well, things aren't going will for the kobold survivors. Some were incinerated, but most got something odd done.
1. A kobold stumbled upon the magma lever, and due to the "More Ways to Kill a Fortress" guide 3'rd edition 3D version blue series, pulls it despite whatever dangerous problems happen to it. Thus magma, demons, curses and badass archaeologists cannot stop the kobold from turning off the magma flow.
2. Another one found a secret staircase to a tower at the top of the mountain. I lead twenty survivors up there, but they get detected by a cat on the way up. Thanks to how cowardly these guys are, they run in the opposite direction down into the fortress. Right into some magma.
3. Due to some odd rolls, a kobold got a strange mood and stole a sheet of paper. "Kobolds and their treasure" handbook by Mr Adom states that kobolds get random loot instead of an artifact for their strange moods. I have the kobold throw the paper away, the worthless thing. Of course, it was no ordinary paper. It was a scroll of genocide. It hits a door, and thus all doors are gone.
4. Three fell down the chasm. They found other kobolds plotting an invasion of the overworld, but convinced them to stop. All thats up there is magma and death. They go down and make a grand city in the deep. They construct homes for dwarves that fall down deep chasms.
5. Another kobold is encased in ice.
6. Another one can now breathe fire. Lacking the fire immune tag, he is more of a bomb than a maga-pest.