How to use "proscenium" in a sentence

When the stage lights were periodically dimmed, a score of revolving crystal ballroom chandeliers cast swirling splinters of color that seemed to coalesce into supernatural forms that capered under the proscenium arch

Standing near the left proscenium pillar, out of the main flow of the party, they nibbled at pieces of cake, talking about Magyck! And then about the law, Charlie and Helen Mainway, Las Vegas real estate - and, by some circuitous route, superhero movies.