Music by Kevin MacLeod. Available under the Creative Commons Attribution 3.0 Unported license. Download link: https://incompetech.com/music/royalty-free/index.html?isrc=USUAN1100885

MacLeod's description:

Genre: Soundtrack
Length: 3:19
Instruments: Strings, Bass Clarinet, Percussion
Tempo: 58

Moody moody dark score. Almost a death march. Loops pretty darned well - but you need to trim the end.
ISRC: US-UAN-11-00885 Dark, Eerie, Epic, Mysterious, Somber, Suspenseful 2011