Guild Wars 2: Secrets of the Obscure Official Soundtrack [First Update] 

The music of this expansion is quite different from the previous soundtracks - on the spotlight we have orchestral brass, strings such as harp and violins, and occasionally wind instruments appear such as flute.
Of course the orchestral music is just a base for beautiful synth melodies and demonic chanting and occasionally with choir.
There are many combat pieces in this expansion that are nothing we have heard before. There is a variety of ambient music pieces - some are mostly orchestral, some have more synth.
This soundtrack is honoring classic fantasy atmosphere, but we can hear some resemblances to Diablo's OST or Genshin Impact for example. Still - it's an original soundtrack and I hope you will enjoy listening to it as I do! :)
edit:
I forgot to add that a few pieces also may remind you about older expansions' OSTs:
'Whispers of the Misplaced' sound a lot like Heart of Thorns's music, especially like "Rata Novus" and "Chak Tunnels".
Memories Forgotten on the other hand may remind you also about Heart of Thorns' battle tracks (though it's just a style of Maclaine), but there is an addition of fujara (read as Fu-ya-rah), which was used several times in the Icebrood Saga (Primordus Rising, Champion of Primordus) - it is a theme of a Dwarf we meet in SOTO - Fyhr, so the crossover is justified.
0:00 Main Theme - Maclaine Diemer
3:11 A Fractured Horizon [Skywatch Archipelago's Theme] - Maclaine Diemer
5:17 Isgarren the Curator - Jarryd Elias
7:36 Whispers of the Misplaced - Maclaine Diemer
9:38 Memories Forgotten - Fyhr's Theme [Skywatch Archipelago Meta Theme] - Maclaine Diemer
11:57 The Beast Emerges [Amnytas Meta Theme] - Maclaine Diemer, Bobby Rose
16:21 Amnytas in Peril [Amnytas' Theme] - Maclaine Diemer
18:52 Flesh and Fever - Bobby Brader
21:09 Curious Allies - Maclaine Diemer
23:27 The Kryptis - Bryan Atkinson
25:42 The Wizards - Maclaine Diemer
27:45 These Ancient Halls [Wizard's Tower Theme] - Maclaine Diemer
29:45 Otherworldly Threats - Bobby Rose
31:56 Malaise - Jaimee Jimin Park
34:14 Peitha's Flame - Peitha's Theme Part 1 - Maclaine Diemer
36:23 To Fell a King - Peitha's Theme Part 2 - Maclaine Diemer
37:47 Eparch's Finest - Bobby Rose, Jarryd Elias
39:56 Might of the Cosmos - Dagda's Theme - Michael Paraskevas
42:13 An Army of Avarice - Bobby Brader
44:28 The Bloodied Lord - Cerus' Theme - Bryan Atkinson
46:40 Strangers Masked in Shadows [Intro Cutscene] - Bryan Atkinson
47:08 Courage and Regret [Mabon Cutscene] - Bryan Atkinson
47:53 A Promise [Dagda and Zojja Cutscene] - Bryan Atkinson
49:29 For the Ward! [In Nayos Cutscene] - Bryan Atkinson