These are homebrew rules that effect the game on a general level.
By Peter Cobcroft at GameBoardGeek.
An added level of detail to help work out direction of lava more easily.
When adding any kind of non-natural room, roll a D6:
|1-3||Flammable door (not stone or magical)|
|4-6||Non-flammable door (stone, magical, crystal etc)|
|Age of Civilisation||+1|
|Miners other than Dwarves and Druegar||-1|
When lava events occur (volcano etc) and start filling the map, the flow is stopped by non-flammable doors and will fill up the area until pressure (if applicable) causes the magma to move upwards.