Ancient Tome of Teleport: Dalaran

Ancient Tome of Teleport: Dalaran teaches all mages how to teleport to the original location of Dalaran - the Dalaran Crater in Hillsbrad Foothills, but high up in the air, necessitating the usage of Blink or Slow Fall.

Source
The tome is found at in the Ancient Tome on a bookshelf in the Athenaeum of the Scarlet Halls behind Flameweaver Koegler. Koegler must have been defeated and looted before the book will become lootable. The tome is available in both normal and heroic mode.