how to do the task of Karazhan opening gate?

The task of Karazhan opening gate is quest in dalaran cardejia,  which is not showing on this map. Only in the middle of dalaran, rhonin inside a place where mythic dungeons you are about to doing it ,those dungeons they are Assault on Violet hold,Blackrook hold, Halls of valors and Vault of the wardens,you can see only if your entering.