Remathilis
Legend
Bold is emphasis. A drow can be a unique cleric of Lolth that has abilities a PC cleric wouldn't have. I have no problem extending that logic to other classes. An elf swordsman who dedicated 200 years to the art of the blade can do things a PC elf isn't able to do. The assassins of the Brotherhood of Shadow engage in foul rituals that allows them to kill with a single stroke and disappear into shadow. The Cult of the Foul Lord are warlocks who engaged in such blasphemous acts they have unlocked magic beyond the ken of most warlocks.Yes, exactly. If a class exists and isn't ties to a specific species or culture (mostly seen as Cleric variants among different monster cultures), it's in theory PC-available; in practice there's some non-adventuring classes that would be extremely dull and boring to play - you sit in town while everyone else goes adventuring - but you still can if you really really want to.
You want those powers? Retire your PC, join their faction, and after years of training, you too can become an NPC with their abilities. If you want to keep adventuring here and now, there is the Player's Handbook.