You see an inactive teleporter.
Location
The boss room of the In Service of Yalahar Quest after the final fight has been instigated.
Notes
It was designed in order to prevent anyone from exiting the room while the battle with Azerus is going on. It will revert to a Magic Forcefield some time after he has died or disappeared.
Looks the same as The Orb of Nature and a Charged Ghost Charm.