Can anyone give me some tips on how to make something light/dark, or make something look like a light is shining on it?
Tough one. very tough. But if its close to blinding light, u can try to make it distruption web, and dark swarm for darkness. Lets see...Also for dark you can liftoff terran buildings (command center, something like that) and disable doodad value (or something like that)
A way to do it if ure REALLY desperate is make the player click on a pylon belonging to him in that area so that the protoss energy support would make the light... but i really doubt u want to do that..
You could try changing the terrain a bit.. some terrains change color for elevation, like high snow and snow have different color. Won't effect the unit though. U can do that using terraining, and if its a movie type scene, and the player who u need to be lighter is blue, u can temporarily give it to light blue, to make the illusion seem complete.. i dont think theres a perfect way to do it though
Casting recall on something might look like it's shining.
Use disabled Terran buildings for darkness and when you want it to be light again, just remove them all.
You should use the Web from a Corsair for lightning.. I guess thats a little stupid... but it could work. I was never able to remove it but you could always have like a corsair in the dark and uses it once in awhile. I don't really know how your map goes. Still i guess its a stupid Idea.
Explosions always give a nice lighting effect. Especially observers. If you want dark you could have cramp areas of vision where the terrain is dark. You could also try disabling vision to remove ligting completely.
actually disabled beacon should work and a observer frozen in a certain location will add a crystal shinning effect since it will look like ....i don't know how you say it in english lol...
and for dark just make that of barracks lifted of & disabled
ADDITION:
the word was blure i think