Cannot complete The Accuser quest

Cannot complete “The Accuser” storyline because the ability “Door of Shadows” is not given. It never appears as a zone ability. Disabling addons, relogging, checking all action bars, spell book, clearing cache, abandoning the quest, leaving the area, nothing makes the ability available. I am effectively stuck at this part of the story and am unable to move forward to unlocking the Maw.

same … so frustrating