I just decided to research this and the three most common answers for how to get it is X amount of Crucible headshots, Dead Orbit random drop, or Crota's End reward but all of those have been proven false. There are a lot of people who think it doesn't exist yet or that no one in the game has it but that is where they are wrong. When the game first came out I played for two months straight and within those two months I ran into the same guy twice who had the Superblack shader, unfortunately at the time I had no idea how big of a deal the shader was going go be so I didn't get any video or photographical evidence and didn't bother asking how he got it since I figured if he had it eventually others would get it and it would be a pretty common thing. But there is 100% for sure a PS4 player out there somewhere who had the shader. The only reason I can think of that would explain why he had it and no one else seems to be able to get it is that it's a reserved shader for devs or something like that, something that only a very small and select group of people were given access to. Either that or it was put in the game and made inaccessible with plans of making it available for a later DLC pack someone glitched or hacked the game and got it before it was supposed to be available to us. Bottom line, someone out there somewhere has it so it's definitely real