Board Thread:Fourth Databook/@comment-4366149-20141122004623/@comment-17623-20141203145513

I believe he's implying that Sasuke as shown the ability to create the black fire without using the technique Amaterasu. If I were a guessing man, he's presenting the argument that creation of the black fire itself is not Amaterasu but well the ability to create the black fire and Amaterasu is "Black Fire over my field of vision", which may or may not be his way of trying to justify "Blaze Release" being its own thing.

If I wanted to be a sonovabitch, I would have to agree with Elvenora and go a step forward, stating that the times we've seen him create black fire without using Amaterasu could very much mean the black fire and Amaterasu are different, and we shouldn't assume we just cast Amaterasu because we don't actually see him do it. But I don't plan to make that argument.