Double Lightning Helix

A cone of lightning erupts from a metal object you are holding. Each creature in a 30-foot cone must make a Constitution saving throw. A creature takes 6d6 lightning damage on a failed save, or half as much on a successful one. A creature that fails its save can't take reactions until the start of its next turn.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the Lightning damage increases by 1d6 for each slot above 3rd.