Thunderbolt Javelin

Simple Melee Weapon. Requires attunement.
When thrown, can turn into a bolt of lightning
5ft wide, extending to a target up to 120ft away.
Each creature in line, excluding the target, must
make a DC13 DEX save, taking 4d6 lightning
dmg, or half as much on a failed save. Turns back
into a javelin on reaching the target. Make a
ranged weapon attack. On a hit, the target takes
normal damage from the javelin, as well as the
original lightning damage. One use per short rest.