Lightning Arrow

level 3 - transmutation
Casting Time: 1 bonus action
Range: Self
Components: V, S
Duration: Concentration, up to 1 minute

Description not available (not OGL).
But here is a summary:

If the attack hits, deals 4d8 Iightning damage. Creatures within 10 ft must succeed on a Dex. save or take 2d8 lightning damage.
Ranger
Player´s Handbook
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