Tuft said:The cliffs are just an evocative simple example. I've had fights in rooms with pits of green slime or molten lava, on spiral ramps curving down into deep caves, in the branches of giganormous trees, on the sloping roof of a wizard's tower, in crumbling, ruined castles, and on barges and boats. All pretty equivalent cases...
I would not say that maps like these are routine, but they are not that uncommon...
Sure. And in all cases, I don't see a problem with pushing people off them. Heck, you can even do it in 3E (bull rush). The lethality or otherwise of the drop is something the DM explicitly controls.