I'm not remotely an expert on this stuff, but Halo Manash is the only one I know of that kind of fulfilled my hopes back when I first heard of the genre in the context of the Diablo soundtracks, and I enjoy their Par-Antra I: VIR album a lot. I guess they're also called "ritual ambient", which is apparently a more tribal/percussive variant of dark ambient or something.
EDIT: Also a fan of Voice of Eye's Transmigration fwiw.