I just had an image come unbidden to mind that I thought I'd share, here. Most of it's component parts[1] already feature in suggestions (it seems) but I don't think this unholy union has ever featured...
Consider the scene: Urist McDwarf awakes from slumber to the sound of battle. Hears the cries of colleagues and the wails of... what? Goblins, Monsters, something bigger and badder? But, it does not matter, for the awakening was prompted by the sound of a klaxon. The klaxon. All is lost. When that alarm goes, those who are not already drafted will not be called upon to save anyoen other than themselves. Quickly checking the bauxite door and examining the bauxite walls, floor and ceiling, Urist heads at last to the bauxite levers.
The first lever shuts the hatches that have been supplying his anteroom's cistern with a constant supply of snow-melt water. The second lever secures the outer and inner doors to his apartment, after withdrawing the small bridge between them. The third lever will, after a small delay, sever the support holding the room to the edge of the overhanging cliff cut out to form the main appartment complex's core, underslung by many similarly equipped accomodation units.
Almost immediately after returning to the bed and gripping the edges in well-drilled anticipation, the inevitable sense of weightlessness arrives. Urist does not pray, for the rationalist within has long since pointed out that the deities concerned already knows one heart and inner nature. To pray would only spoil the possibly final moments, or else bring upon a wave of wrath for daring to repent a long-spent apathy. All this and more goes through Urist's mind as the rush of descent sends brain and body on its way.
SPLASH!
Urist is personally unfamilar with the concept of concrete, though would recognise its similarities and differences with some of the rocks encountered over the years since first taking a pick in hands. If hitting water from a great height can be compared to striking concrete, though, the slight but significant mitigation arising from the room-pod's landing in boiling river of magma probably tips the balance towards survival, in addition to the bed's specially scored legs giving way immediately after.
Crunch! Oh well, a chamber pot is replacable, if anything is.
And now the magic of enhanced magma-safe materials comes to life, as the cooling cistern collapses and a shallow wave of ice-cool water floods across the underfloor of the room, before venting above. For a short time, this will keep Urist comfortable. But with a history in the magma furnaces it should be no hardship.
Gloopily, the room settles higher in the liquid. The weight of its building materials offset by the density of the magma stream itself, causing it to ride high as it drifts along, driven by the slow but relentless current. And eventually to reach the secured lower reaches of the magma cavern. While awaiting the arrival, Urist inspects the integrity of the Escape Pod, and ponders the fate of those whose wooden quarters are set adrift in the rivers. Lighter, yes, but more unreliable, and that third-placed liquid, water. Suitable only for invalids, filled with Carp, far less reliable with its constant freezing and evaporating.
With a mumfled 'Clunk!', the drifting motion stops. A slight wallowing motion remains as Urist considers. Having lost track of time, during the musings, it doesn't really seem long enough to have made the full journey to the Hot regroup point, but with high Imagination and Intellectual quotients such a time-slip is nothing new. Here goes, then. Put on the spare leather armour. Equip the backpack. Fill the waterskin with some of the remaining snow-melt supply, and darn to heck the rules regarding flammable alcohol storage in Magma Escape Pods. And having drunk his last illicit cask two nights beforehand.
Now to break the seals on the upper hatch. The future awaits. Urist's skills may now be tested to the limit in the creation of a new Moutainhome over the next few seasons. Or almost immediately merely in order to survive whatever unknown threat lies in wait outside this refuge. Can you hear faint tapping? Pull the final lever and see...
[1] Moving architecture, floating, mega-engineered magmaducts, new migrations, etc, etc...