Hurricane Harpoon

Weapon (javelin), legendary (requires attunement)

This harpoon (treat as a javelin) has a head of mithral and barbs of coral or whalebone.

You gain a +1 bonus on attack and damage rolls with this weapon, and it also has the stormshaft minor weapon property (see page 109). 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. Make a ranged weapon attack against the target. On a hit, the target takes damage from the harpoon plus 4d6 lightning damage. In addition, each creature in the line excluding you and the target must make a DC 15 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 harpoon when it reaches the target and it then reappears in your hand.

The hurricane harpoon can shroud you in a whirling screen of strong, howling wind. While this effect is active attack rolls against you are at a disadvantage and all melee attackers (including those using reach weapons) must make a DC 15 Strength saving throw or be pushed back 10-feet and be knocked prone. This effect lasts 1 minute.

In addition, once per day you can control winds within 5 miles of you. This acts as a control weather spell but only effects wind conditions. Any ship upon which you stand are unaffected by this effect unless you wish otherwise.

Finally, if you are targeted with an effect that deals lightning or thunder damage, you become shrouded with gale-force winds riddled with crackling lightning and peals of thunder. The effect provides damage resistance to both lightning and thunder to the triggering attack until the end of your next turn.

While so shrouded, whenever a creature within 5 feet of you hits with a melee attack, the shield erupts with lightning. The attacker takes 2d8 lightning and thunder damage. This effect consumes the wielder’s reaction.

Each effect once used can’t be used again until the next dawn. In the meantime, the harpoon can still be used as a magic weapon.