By build levels I mean layout props, buildings on the fly. Obviously would have to be pre-designed so you could just plonk something down (which is where the toolset comes in). I would like to be able to sculpt terrain on the fly but that is wishful thinking on my part which is why its on my nice to have list. Even if just to simulate town destruction or some cataclysmic event like meteor strikes.
A lot of that stuff can all be done using offline/author-tools hopefully. For example, in NWO I have a quest where you need to try and save a small village from an attack by fire gnolls. They attack several buildings and using trigger conditions I was able to "disappear when" the pristine building, and "appear when" a firey/burning/destroyed building. This was simply using trigger conditions --- like the fire gnolls "reached" a building, and a few seconds later were able to "ignite" it. All done without a live GM.
With a live GM it would definitely be nice to be able to "plop down" graphic objects -- buildings, collapsed cave rubble, debris, catapult impacts, fires, smoke, effects, etc. You almost assuredly don't need the intricate detail of being able to x/y/z position and rotate yaw/pitch/rotation objects. Although, if the toolset allows you to create a GM "palette" of pre-scaled/rotated objects that you can then simply pick-and-drop that might be useful.
"Landscape" adjustments could be done to a minor effect on the fly as well as long as we're given "large" terrain objects -- boulders, small hills, cliff edges, cavern openings, etc.
The realtime GM tools definitely need to be easily usable and quick to select.
A mashup of SCL "GM" mode, NWO scene/adventure/dialog building, and NWN Scripting would probably make me wet myself.
