Lovecraft's Horrors: "Call of the Cthulhu" World.

This staff can be wielded as a magic quarterstaff that grants a +3 bonus to attack and damage rolls made with it. The staff has 10 charges. When you hit with a melee attack using it, you can expend up to 3 of its charges. For each charge you expend, the target takes an extra 1d6 force damage. The staff regains 1d6 + 4 expended charges daily at dawn. If you expend the last charge, roll a d20. On a 1, the staff becomes a nonmagical quarterstaff.