While wearing this ring, you have +1 bonus to unarmed attack and damage rolls. This ring gains 1 charge every time you score a critical hit with an unarmed attack, to a maximum of 6 charges. By spending 3/6 charges you can cast Lightning Bolt at 3rd/6th level as an action.
If you expend the last charge, roll a d20. On a 1, the ring loses its properties and becomes a nonmagical ring.