Lesser Mana Battery

On a hit with an attack, you can choose to expend
any number of charges, dealing an additional 1d6 Force damage per charge expended. This damage affects only one creature per attack.

The Battery has 5 charges. It regains 1 charge per spell level stored into the Battery. If you expend the last charge, roll a d20. On a 1, the Battery becomes inert and loses all magical properties.