An Arm-Mounted Harpoon Cannon is a magic weapon that attaches to your arm, becoming inseparable from you as long as you're attuned to it. To attune to this item, you must hold it against your forearm for the entire attunement period.
This weapon uses spears as ammo.
As an action, you can free-fire the spear from your forearm to make a ranged attack (range 80/320) that deals 1d6 piercing damage.
While it is attached to a rope you can make a ranged attack (range 20/60) that deals 1d6 piercing damage. On a hit, the creature is also grappled and cannot move further away from you. The creature can use its action to make a strength check against your DC (8 + your proficiency bonus + your strength modifier). On a success, the creature takes 1d6 piercing damage as it removes the spear and is no longer grappled in this way. While a creature is grappled in this way you can make a contested Athletics check against the creature. If you succeed, you can pull the creature toward you up to a number of feet equal to 5 x your strength modifier. If this brings the creature within 5 feet of you, you can use a bonus action to make one melee attack against that creature.
While the Arm-Mounted Harpoon Cannon has a spear loaded you can use the weapon as if you were holding it, and you can't use that hand for other purposes.
You can detach or reattach it as an action, and it can’t be removed by anyone else.
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