Someone much more dedicated than I am could turn that slip-and-fall mechanic into an overpowered trap. See, fall damage is proportional to the density of the material that collides with your victim; the denser the material, the greater the damage. Presumably, ramps/stairs made out of platinum bars would spell instant death for your enemies if they slipped. How you'd go about doing that without causing the deaths of 90% of your dwarves in the process is an exercise left to the reader.
beaten to death by granite staircase
All rock is living, and every 5000 ticks, a random thing made out of rock will suddenly reanimate and fight your dwarves. It's like The Earth Strikes Back, but somehow even more hardcore.