Staff of the Destroyer

The Staff of the Destroyer is an ancient and ornamental staff carried by Imotekh the Stormlord. This staff was first wielded by Zehet, the founder of the Zehet Dynasty. This staff has been wielded by every single one of Zehet's successors. It is not only a symbol of rank for Imotekh, but it is also an unbelievably powerful weapon. In battle, it can unleash a searing beam of pan-dimensional energy that can make a mockery of even the most heavily armoured foes. However, there is hope for Imotekh's enemies, as the staff takes time to recharge its power.

Source
Codex: Necrons  (5th Edition), pg. 55