Source: Explorer's Guide to Wildemount

Rod, uncommon (requires attunement)

This adamantine rod is tipped with a glowing crystalline eye. The rod has 3 charges and regains all its expended charges daily at dawn.

When a creature you can see within 60 feet of you damages you while you are holding this rod, you can use your reaction to expend 1 of the rod's charges to force the creature to make a DC 13 Dexterity saving throw. The creature takes 2d10 lightning damage on a failed save, or half as much damage on a successful one.