For all the reasons to love Opera IX, it's really the keyboard sounds that pushes Fronds of the Ancient Walnut into !!!!! territory for me. I love how progressively Opera IX moves from blast beats and shrieks to operatic moaning over midtempo beatdowns. Certainly there's a lot of gothic posturing, pagan imagery and classical influx at play. But it's those fuckin keyboard sounds that sound like the "boss theme" from some RPG, mixed with the guitarist shredding in a completely different key...can't beat it. Makes me want to listen to some Enslaved By Owls, who more than anybody else know how to use ominous, outsider keyboards to make heavy and evil music without even needing a distortion pedal.
As a bonus, I've also got a free download of Opera IX's first official release, 1993's 7" consisting of Born In The Grave / The Red Death. No keyboards on this one, but hey, still some great, strange blackened sounds for ya.