It would take forever to go through all or most of them but ill go through the ones i particularly like or think you may be interested in.
Agalloch- Doomy, folky (kinda like eluveitie) black type metal. A pretty eclectic mix. DEFINITELY worth checking out.
Autopsy- Classic death metal in the vein of death, deicide ect. 80s and early 90s. No "core" bullshit.
Ahab- "funeral doom" similar to candlemass.
Fuck that way, it'll take forever hahaha. Ill bold some of the more definitive bands or ones you should realllly check out. Some bands will appear more than once due to genres overlapping .
Really good old black metal bands from list, some folk metal- Bathory, Belphagor, BURZUM, Emperor, Behemoth (polish death metal/black metal), Carpathian forest, Gogoroth, Hellhammer, Mayhem, Mercyful fate (king diamonds first band, only sorta kinda black metal lol. still badass), Venom, Ulver, Immortal, Leviathan
Doom metal and doom subgenres- Ahab, Burzum, Down (phil anselmos stoner doom/southern doom band), Electric Wizard, Funeral, Heaven and Hell (members of sabbath playing mostly dio sabbath), Isis, Neurosis, Om, Saint Vitus, SLEEP.
GOOD Death metal (no "core" or lame assed breakdowns)- Autopsy, Bolt thrower, Death, Deicide, Dismember, Dissection, Entombed, Gogoroth (seriously some of the most tech and heavy shit ever.), Hellhammer, Kreator, MORBID ANGEL, Pentagram, Possessed, Terrorizer (kinda grindy, extreme)
random stuff worth mentioning - At The gates (pretty good progressive stuff, not exactly my cup of tea but worth checking out), Hawkwind (lemmys first band), Manowar, Poison (cheesy hair metal), SEPULTURA, Slayer, Yes (hahahahahahah just do it)
Your friend had some good taste in music, I quite like the death metal selection he threw in there. Almost all of it was CLASSIC death metal, some great black metal in there too. Alot of the stuff on the list was kinda old (which is to my liking) and may not have the greatest recordings, but its worth toughing out.