The Civil Wars - "Kingdom Come"
In addition to collaborating with Taylor Swift, Grammy winners The Civil Wars contributed a song of their own to the OST. "Kingdom Come" is full of all that I love from this duo - haunting (yes, I know I use that word every time) harmonies, minimal instrumentals, & a soft beginning that effortlessly segues into a desperate climax. The theme of "running" is very appropriate for a film that's about a forced fight to the death, or, on a larger scale, the iron hand of the rulers over their downtrodden citizens.
Punch Brothers - "Dark Days"
"Dark Days" by American progressive bluegrass band Punch Brothers (who are not actual brothers) is another dark (natch) song, very fitting. The opening notes on the banjo with the accompanying deep beat are wonderful, but without a doubt the strongest section is Gabe Witcher's fiddle. This song perfectly captures the secondary theme of the film - love. The love the heroine has for her sister that propels her into the events of the film, the tenuous love triangle only hinted at, the burgeoning feelings between the main characters, a brief friendship between the heroine and a doomed young girl. Punch Brothers manages to touch on melancholy without delving into depression, keeping just a hint of an uplifting spirit.
The soundtrack is full of other incredible artists such as Arcade Fire, so don't be afraid to check it out simply because I only like two songs. Like I said, I listened as someone who is familiar with the source material.