We've seen many harpies during Legion but where is Aviana? Isn't she their leader? Why is the Cenarion Circle fine with one of their holy wild gods allowing her brethren to kill their own druids and other innocents? Well I guess Blizzard has forgotten about her or they're planning something big.
Harpies have been watching us in every zone as we battle the Legion. There has to be more to it than them just being there for show. What if they are holding the key to the Shadowlands? Everyone has been wondering about why the Shadowlands is locked from the mortals. Shadow Magic has been in the game since vanilla but we've never seen the actual Shadowlands. Blizzard should fix that.