The holy item was created long before the god’s death during the Time of Troubles. It was wielded by the High Priests of Myrkul of the temple under Waterdeep in Undermountain. After the Time of Troubles, the temple was mostly abandoned, with undead guardians left to deter any opportunistic adventurers from pillaging the temple. The wand itself was hidden inside a well-protected vault and stayed there until 1370 DR.
In 1370 DR, Khelben Arunsun stumbled upon information of the Black Wand's existence and its location right under the Khelben “Blackstaff” Arunsun's nose. Still filled with hate for the dead god over taking control of his love, Laeral Silverhand in 1337 DR, Khelben seized the opportunity to destroy the bit of Myrkul's divine essence within the wand.