Aerar's Striking Javelin

You touch a nonmagical javelin. Until the spell ends, that weapon becomes a magic weapon Imbued with lighting energy. When you hit with a ranged attack using this javelin it deals 1d6 lightning damage plus strength mod to the target then transforms into a bolt of lightning, forming a line 50 feet long and 5 feet wide that extends out from the target as if continuing in the direction thrown. Each creature in the line including the target must make a Dexterity saving throw. A creature takes 4d6 lightning damage on a failed save, or half as much damage on a successful one.

The lightning ignites flammable objects in the area that aren't being worn or carried. When the spell ends the javelin turns to ash.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, you may imbue an additional javelin for each slot level above 2nd.