[2] During April 2012 Insomnium returned to tour the U.K. as the main support act for British gothic metal band Paradise Lost.

On 19 September 2013, Insomnium released "Ephemeral", a single from their foreshadowed 2014 album, Shadows of the Dying Sun, via Century Media Records.

It is a concept album consisting of a single epic 40-minute track, and it is said to be about "a group of Vikings who set out to find a fabled island west of Ireland, despite the treacherous winter drawing near.

"[4] This album was based on the short story by Niilo, "Winter's Gate", or "Talven Portti" in the original Finnish.

With the album announcement they also confirmed that the guitarist Jani Liimatainen had joined the band as a full-time member, as he had occasionally filled in for Ville Friman on tours since 2015.