Re: Several questions - light rays, non-magical hero retinue, hero retinue instead of lord, large or not units, unassailable chaos armies
You mentioned that you're playing the Vortex Campaign. The light beams look like the beams that appear in the Vortex Campaign when a ritual is happening, as shown in this article.
You asked which units are large. According to a Warhammer Wiki:
Units are either considered large or small. Infantry, war beasts, and most artillery crews are small. Cavalry, chariots, war machines, monstrous infantry, and monsters are large.