Most technically proficient guitarists possess the ability to write the riffs themselves, but the genius of Mütiilation - esp. circa Vampires/Remains - is that Mey'nach had and has a level of compositional skill that lets him arrange them into some of the greatest BM songs of all time.
Some Black Metal requirements:
Graveland - Thousand Swords
Burzum - Burzum
Bathory - Under The Sign Of The Black Mark
Immortal - Pure Holocaust
Nokturnal Mortum - Nechrist
Necromantia - Crossing The Fiery Paths
Summoning - Minas Morgul
All of these should be relatively easy to find online...
I'd recommend buying the Effigy Of The Forgotten/Pierced From Within reissue; The End has it for $16. That's two excellent albums at a very good price.
Atheist, The Chasm, Immolation, Vader, Suffocation, early ATG, early Deicide, Demigod, Demilich
also, [obligatory Soulside Journey whoring]
Death released one great album and some decent Possessed worship.
Oh, I can fix that, good sir.
1981: Venom - Welcome To Hell
1982: Venom - Black Metal
1983: Slayer - Welcome To Hell
1984: Bathory - Bathory / Sodom - In The Sign Of Evil / Hellhammer - Apocalyptic Raids
1985: Bathory - The Return... / Exodus - Bonded By Blood
1986: Bathory - Under The Sign Of...
My first was Hvis Lyset Tar Oss, but Burzum/Aske or Det Som Engang Var would probably be better to start with; but don't get me wrong - HLTO was definitely one of, if not the best thing Vikernes recorded under the Burzum project.