This javelin is a magic weapon. When you hurl it and speak its 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 in the line excluding you and the target must make a DC 13 Dexterity saving throw, taking 4d6 lightning damage on a failed save, and half as much damage on a successful one. The lightning bolt turns back into a javelin when it reaches the target. Make a ranged weapon attack against the target. On a hit, the target takes damage from the javelin plus 4d6 lightning damage.
The javelin's property can't be used again until the next dawn. In the meantime, the javelin can still be used as a magic weapon.
If a weapon has the thrown property, you can throw the weapon to make a ranged attack. If the weapon is a melee weapon, you use the same ability modifier for that attack roll and damage roll that you would use for a melee attack with the weapon. For example, if you throw a handaxe, you use your Strength, but if you throw a dagger, you can use either your Strength or your Dexterity, since the dagger has the finesse property.
Each time you make an attack roll with this magic weapon and hit, you can have it deal Lightning damage instead of Piercing damage.
When you throw this weapon at a target no farther than 120 feet from you, you can forgo making a ranged attack roll and instead turn the weapon into a bolt of lightning. This bolt forms a 5-foot-wide Line [Area of Effect] between you and the target. The target and each other creature in the Line [Area of Effect] (excluding you) makes a DC 13 Dexterity saving throw, taking 4d6 Lightning damage on a failed save or half as much damage on a successful one. Immediately after dealing this damage, the weapon reappears in your hand. This property can't be used again until the next dawn.
If a weapon has the Thrown property, you can throw the weapon to make a ranged attack, and you can draw that weapon as part of the attack. If the weapon is a Melee weapon, use the same ability modifier for the attack and damage rolls that you use for a melee attack with that weapon.
If you hit a creature with this weapon and deal damage to it, you can reduce its Speed by 10 feet until the start of your next turn. If the creature is hit more than once by weapons that have this property, the Speed reduction doesn't exceed 10 feet.