For example if we used some of the dark theme'd blues, tendrils, crows, souls magic of course could be similar to the Nu Mou, maybe blood magic. Or, potentially could relate to emotion.. magic. Before people go on lore, obviously a lot of stuff would need to be worked out based on whatever is picked. . . I'm trying to not have a 10k+ post here, help me okay lol (could wing some concepts later if need be). For the blood effect it would have to account for undead, like it turns into a dusty / particle mist blue effect (to represent draining of magical essence from undead), in a sense building a sort of vampire warlock job (or Lich of some sort, give it that FFXI blue mage like back story >:3). I'm aware Red Mage has the lore for vampire, but we can take that concept and run down it 200 miles an hour plus some twists so it's not literally a red mage gone bad (different techniques some vaguely similar concepts, like using math to make rockets or using it to make bridges).
Since we did get Reaper though, I mean to ask- is it the visual colors or the thematic vibe that is the desire? Like shadow-y warlock, Ascian vibes included, the thought of void magic specifically, black colors, taboo or mysterious nature, armor set important (which armor silhouette, cloaks?), weapon idea, etc, ? Say for example if it was a taboo magical focused job with dark elements of theme but was largely a job using colors not specifically black (or at least exclusively)?