Halo 4 forge option
I think you should be able to change the weather of your map that you make in forge. For an example, if your making an infection map you can change it to a thunder storm or you could use the idea for machinimas.
HALO 4 best forge
Be able to spawn an none stop of what ever you want. For example, I can spawn 20 war hogs then blow them all up. I think people would make the best forge sculptures that would amaze 343 and halo 4 players.