I want black metal that is epic not in the Bathory-ian sense (meaning, slow and brooding) even though, of course, some elements of it wouldn't be a problem (I do like that style, just got a bit tired of it since everybody these days seems to be playing it)

The black metal I'm more interested in, is the kind that is being played by "good guitarists", let's say. I notice that the bands I'm more interested in bear a Emperor/Dissection influence, hence the title (Taake of the 2nd album would be a good reference too). The riffs have to be top notch and the composition should be very 'ambitious' with some complexity (hence the 'prog' part, don't want it to sound like Rush). The guitars should have speed/thrash and heavy metal riffing and not tremolo playing all the time. If the aesthetic/lyrics/concepts is medievalist/fantasy too, then we're talking about the absolute match.

(Yeah, my fantasy is the total rpg-guitar nerd black metal band, you got it)

Some of my fave bands that somewhat fit into that style:

Artefact (and the next band Aldebaran did after their demise, Darkenhold, the best example of what I'm looking for)

http://www.youtube.com/watch?v=YU2qcK_0ZfQ
http://www.youtube.com/watch?v=czHhmj98Mo0

Arkheth - doesn't really have the speed/thrash elements, but perfect example of the "ambitious spirit", their second album is a 2cds concept, 120 min length for fuck's sake.

http://www.youtube.com/watch?v=ufMyHCT5NPA

Xanthochroid - This is supposed to be "symphonic" and while I'm not interested in a lot of keyboards and pianos or acoustic parts (and while it obviously lacks in bm elements) this is a great example of 'prog' bm-related writing.

http://www.youtube.com/watch?v=kI7F2GrNJtE

No Hand Path - Lacking hyperactivity in the guitar department, but quite good.

http://www.youtube.com/watch?v=CQWQeFNSoss

I guess I'm mainly looking for underground bands since the chances I haven't heard something mainstream are slim. (And no Bal Sagoth, please)

Is Sirius considered mainstream by your standards? I can vouch for their first album, it's beastly. Not nearly as "progressive" as you may want it to be but I feel that it captures almost a bit of every Emperor album, has a fantastic use of keys and kick ass riffs.

Ceremonial Castings? maybe lacking a bit in the speed/thrash/prog/dept. but give it a shot

http://www.youtube.com/watch?v=Fmitxr-EAQw

Neither of the two suggestions were very close, but interesting nonetheless. I guess I should have avoided putting Emperor first, what I'm looking for is something inbetween Dissection's "Storm.." and Artefact's "Ruins". The closest Emperor have got to that is somewhere between "Anthems.." and "IX Equillibrium", not the debut. These two (especially Sirius, which I was aware of but hadn't heard) are more like classic symphonic black metal from the 90's, Emperor's first and Limbonic Art oriented. "Aeons of Magic" does sound promising though, I'll keep listening! Ceremonial Castings is a bit of a strange beast, eh? They seem somewhat cliched and "naive" for lack of a better word, but there are some interesting elements there.

To further clarify; what I'm looking for is guitar oriented, like Dissection and Artefact. It doesn't matter if there are some symphonic elements and keys, but they shouldn't be dominating. Thanks on these first two suggestions though.