I've just experimented with the lightning effect and embedded the result as a comp into a particle system to create the change in size (actually depth - because of a 3d set-up). Combined with the randomness of color of each particle between black and white I was able to create a random appearing of the lightnings. (I've used a black background plane in order to make the black lightnings invisible and embedded this comp into a third with blending mode add). You can see the result here.
If that is ok, I'm going to keep this thread as a personal thread for showing you my little projects. Have a good day!