Shock Arrow (5e Equipment)
From D&D Wiki
Weapon (arrow), rare
This magic arrow is has pronged, jagged arrowhead reminiscent of a lightning bolt. Once this arrow is drawn, you can use your bonus action to focus on the arrow, causing it to audibly crackle with static. If you use this crackling arrow as part of a ranged attack before the start of your next turn, the attack deals lightning damage instead of its normal damage type. The hit target must succeed on a DC 15 Constitution saving throw or be stunned by electric shocks, and drop anything it is carrying, until the end of its next turn. If the target has resistance or immunity to lightning damage, it automatically succeeds on this saving throw.
Once it hits a target, this arrow is no longer magical.
You can expend 1 magic point when you use the bonus action to have this attack deal an extra 1d6 lightning damage. If you have the Spellcasting feature when you do this, the DC becomes equal to your spell save DC if it would otherwise be lower.