This quest is not available in game.
Use the Arcanite Buoy at the Swirling Maelstrom at the Bay of Storms in Azshara.
Did I mention the bad news yet? Its name is Maws: 100 feet of death and destruction. I guess I may have forgotten that little tidbit.
According to my superior psycho-psionic clairvoyance, you'll find that the best spot to cast this buoy is off the coast of Azshara, in the Bay of Storms.
Look for a swirling maelstrom, most likely cluttered with wreckage.
By the by, I hope you have friends.
Now if you somehow miraculously succeed, take the scepter shard to Anachronos.