We often talk about the music that is added to the episodes and how great a job they did first season. I think they're doing a good job this season also and, after repeated viewings of this episode, I really noticed its impact - specifically during the fight scene. The Christmas music at the beginning of the scene was, at first, almost a distraction but, now I see how it actually helped build the intensity of the fight.
The part that I really noticed was during the fight on the street. I'm not sure what the music was, or who the composer is, but the score was timed very well with what was going on in the fight. Specifically, how the instruments changed from a lighter (maybe clarinets, violins??) to deeper instruments (maybe tuba's and trombones?) when Reign headbutted Kara and she dropped to the ground and then crawled up the street. That change really emphasized to the viewer that, it was at that moment that the momentum of the fight had changed and that things were not going to go well for Kara. Great job!
--Sorry for the lack of musical technical terms or knowledge, my musical background consists entirely of listening pleasure only.
the music I noted the most the entire episode was Kara slowly, step-by-step, making it to the top of the street rubble. Totally ominous!