[Scarblac]

And that several internal organs of a dwarf are simulated separately. Some of them are fat, and fat has a relatively low melting point. Some rooms got warm enough (because lava was running through nearby rock) to melt the fat, killing the dwarves.

The bug was, iirc, that the AI didn't route around this effect.

Of course, for a long time making rooms like this and leading enemy armies through them was an important part of fortress defense, because actual militias were so bugged at the time...

Also insanely strong carps that drag dwarves into the water, killing them. After all, swimming is exercise, it trains strength, and carp swim all day long...

[Arrath]

IIRC, it used to be that very rarely a dwarf might survive the process of having all their fat melted off. This served to turn them into little Terminators, as they had little left that could catch fire again and their nerves were cauterized by the experience so they couldn't feel pain any more.