Board Thread:Warhammer 40k General Discussion/@comment-9676764-20140120182122/@comment-2093048-20140120192039

There was a loyalist Thousand Son from the Horus Heresy era who states the Blood Raven quote "Knowledge is power" and has a name very similar to the Blood Raven's famous chapter master (or something like that), and uses Raven iconography.

If that doesn't hammer the point home like all the other miscellaneous clues going around and that "Ravens crying tears of blood" prophecy did, then nothing will.