I have looked through the entire cave in the Crumbling Depths in Deepholm and can’t find the Dark Fissure. I have even used TomTom to locate it’s exact location and the fissure is still nowhere to be found.
Is it still possible to get to the dark fissure to get the Lucid Nightmare?
EDIT: I went back to Ahn’Qiraj and read the message that was left after solving the puzzle. Now in Deepholm, the Dark Fissure appears.