If you haven't already, please be sure you set some time aside to study Aris' forum post with everything you'll need to know going into Legion. Aris and Total have been working increadiably hard outside of raid to put this thread together and Total has posted several videos with useful information that you'll be needing. And if you're a complete lazy pos, Total has even kindly written up a tl;dr post containing only the increadibly vital information that you'll need.