Javelin of Lightning

When you hurl it and speak a command word, it transforms into a bolt of lightning, forming a line
5 feet wide that extends out from you to a target
within 120 feet. Each creature and the target must
make a DC 13 Dexterity saving throw, taking 4d6 lightning damage or half as much with on a save.
The lightning bolt turns back into a javelin when it reaches the target. Make an attack against the target. On a hit, the target takes 1D6 + 4d6 lightning. This property can't be used again until the next d