The mithril wizard's staff[1] grants a basic lightning attack that can chain to two additional enemies. It's the most powerful among the craftable staffs.
↑As it appears in the inventory. In the game files it's called mstaff_mithril.
↑0.9.016 notes say a new item called "mithril staff" was added to the game. It refers though to the wizard's staff that required mithril ores to be crafted at that time.