The 2010 Sleepthief song “Empyrean” featuring Suzanne Perry’s classic glossolalia style vocals is included on the 2015 expanded version of Labyrinthine Heart. This song was previously only available on a Barnes & Noble exclusive compilation CD, making this the first time it’s been available on streaming services. “Empyrean” is 1 of 4 bonus tracks added to the 2009 album, which also features updated artwork.