Here's a list of bands I've found avant-garde in the last month to two months:
Burst, get their 2008 album Lazarus Bird
Candiria, get their albums from 1997 & 1999
Ephel Duath, get The Painter's Palette (has lots of saxophone, people describe this album as "jazz metal" lol, though Pain Necessary To Know focuses on more jazz guitar and random staccato riff breaks in many sections which I found irritating but it was still a cool find regardless)
Fredrik Thordendal, his only album called Sol Niger Within deals with lots of metal riffage at groove tempos and his signature Holdsworth influenced jazz fusion solos and also becomes experimental. For the guys that love epic length albums on a single track.
Ihsahn, everybody has After by now right.
(forgot a strong recommendation! if you were to check out something from this list, pick this first) Yakuza, I really enjoyed Transmutations
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That's it for now.