Rod of the Sleepwalker is a rare staff with very impressive bonuses to intellect and spirit, making it an obvious choice for any magic-using class.
This item drops from Twilight Lord Bathiel in Blackfathom Deeps.
This section concerns content exclusive to the Warcraft RPG, and thus unlikely to be canon.
"An egg-sized blue gem glitters atop a length of gnarled and twisted wood. The gem sheds an arcane glow that illuminates the length of the staff.
The origin of the rod of the sleepwalker remains shrouded in mystery, but it belongs to Twilight Lord Kelris of the Twilight’s Hammer." (DF 95)