Kalytha’s Haunted Locket is sold by Tex Vortacoil (a Goblin vendor) in Xylem’s Tower, Azshara for 5k Gold. The item transforms you into the ghostly female Night Elf Kalytha. The item has a 15min CD and lasts 30mins. If you don’t mind parting with that much Gold you actually get a pretty nifty item. Notice that the buff lasts longer than its CD. May be more fun for Horde characters though. You’ll be able to see your own weapons and do not need to equip the item.

Kalytha's Haunted Locket
Kalytha's Haunted Locket + Leyara's Locket + Vyrkul's Drinking Horn

Thanks to Navimie and Roshii for this one :)