Quote from malonedog24 >>

Just bought this - can't wait to try it out!  Will post updates :)

 All account activity ended about two weeks after this comment exactly. I hope they’re okay...

That is an awesome idea! Must have made the DM's life hard to balance combat around that. Did you start seeing a lot of monsters with resistance up lightning damage?

What other methods of crafting this, aside the smiths tools and someone casting lighting into it would you consider valid ways of crafting one?

So, TCoE added the Maneuver "Quick Toss".

This lets you take a Bonus Action to draw and throw a Thrown weapon (any Thrown weapon), adding your superiority die to the damage.

Additionally, you can take the "Thrown Weapon Fighting" Fighting Style (also from TCoE) and add a bonus +2 to the damage!

In conclusion, Bonus Action javelin of lightning that does up to +14 extra damage (at 18th level) when it hits the end target :D

Quote from Discombobulator >>

So, TCoE added the Maneuver "Quick Toss".

This lets you take a Bonus Action to draw and throw a Thrown weapon (any Thrown weapon), adding your superiority die to the damage.

Additionally, you can take the "Thrown Weapon Fighting" Fighting Style (also from TCoE) and add a bonus +2 to the damage!

In conclusion, Bonus Action javelin of lightning that does up to +14 extra damage (at 18th level) when it hits the end target :D

 That. Is. AMAZING!!!

what level can u safly give it to your players with out it being op asf

ayeeeee my tempest cleric also has this lol it's so dope. i would rage if it was stolen from me, rip

Quote from Jerther >>

I guess it depends on the scenario, but doesnt seem like you could hit too many in a row before your target would be considered in total cover.

 Looking over this again as a magic item to award to one of my players. And it would diminish its usefulness if it remained a physical weapon, bound by the rules of cover. However “…it transforms into a bolt of lightning…” “The lightning bolt turns back into a javelin when it reaches the target.” It actually becomes lightning. So it is basically just like the lightning bolt spell. It behaves like a line spell, that then rematerializes on impact. Pretty flavorful. I love it.

My barbarian player loves this thing, but he always forgets to pick it back up. I think I'm gonna make a Javelin of Cold for the Paladin, who has a desperate need of ranged weapons.

yeet 

la yeet

Quote from steelwolf17 >>

what level can u safly give it to your players with out it being op asf

Probably level 5, since that's the level they start getting things like Lightning Bolt and Fireball, and the DC here is only 13.

To be clear, "each creature in the line excluding you and the target, " means that it is a half-lightning bolt on creatures between the attacker and the target, NOT the target. The target takes the weapon damage + 4d6 lightning damage if the ranged attack hits, and 0 damage if it doesn't. The potential damage is still great, but nowhere near game-breaking as a once per day ability.

Also, if the players aren't careful, enemies can just pick up and run off with the javelin. Example: if it were a bunch of goblins, and one of them lived to see the javelin land, I'd say that one would almost certainly pick it up and try to bolt with it (no pun intended). And if the players couldn't track that goblin down, or at least find the goblin burrow, bye bye javelin.

As an interesting sidenote, RAW the attacker makes a ranged weapon attack, not a thrown melee weapon (javelin) attack. This should mean using DEX to calculate the to hit and weapon damage instead of the STR normally used for javelins as a thrown melee weapon. This creates an annoying situation where you want DEX for the special ability, but want STR for the base javelin that bypasses resistance to non-magical weapon attacks. Although, I'd never enforce this, personally.

My paladin mixes this up with Branding Smite, because it's the only Smite spell that specifies on Weapon Attack and not Melee Weapon Attack, and it's pretty freaking great.

Quote from Infuser >>

Quote from steelwolf17 >>

what level can u safly give it to your players with out it being op asf

Probably level 5, since that's the level they start getting things like Lightning Bolt and Fireball, and the DC here is only 13.

To be clear, "each creature in the line excluding you and the target, " means that it is a half-lightning bolt on creatures between the attacker and the target, NOT the target. The target takes the weapon damage + 4d6 lightning damage if the ranged attack hits, and 0 damage if it doesn't. The potential damage is still great, but nowhere near game-breaking as a once per day ability.

Also, if the players aren't careful, enemies can just pick up and run off with the javelin. Example: if it were a bunch of goblins, and one of them lived to see the javelin land, I'd say that one would almost certainly pick it up and try to bolt with it (no pun intended). And if the players couldn't track that goblin down, or at least find the goblin burrow, bye bye javelin.

As an interesting sidenote, RAW the attacker makes a ranged weapon attack, not a thrown melee weapon (javelin) attack. This should mean using DEX to calculate the to hit and weapon damage instead of the STR normally used for javelins as a thrown melee weapon. This creates an annoying situation where you want DEX for the special ability, but want STR for the base javelin that bypasses resistance to non-magical weapon attacks. Although, I'd never enforce this, personally.

 
Thrown is a  property that allows a ranged attack not a kind of attack. So ranged attack can mean a thrown attack which means you use strength when you throw this weapon assuming it inherits all the properties of a javelin.   

Thrown. 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.

As no one else mentioned it regarding the idea of using nf an Artificer infusion technically you can't. Infusions can only be applied to mundane items so since this is already a magical item it is ineligible.

I'd allow it at my table but RAW says no.

If you were looking for a more powerful version of this you could always make it require attunement. That way it could keep the +1d6 lighting damage every attack, return after the attack is made and then 1/day use the lighting attack as noted. 

Quote from DiceFarmer >>

That's assuming the enemy you just hurled it at doesn't decide to pick it up and throw it right back at you!

 It would just be a regular magic javelin unless dawn broke between turns. I'd pay a probably max 11-13 HP tax to not worry about having to retrieve my javelin lol

how much does it cost

use an artificer to add the return item infusion

you can go recover it after throwing.