Harpoon (5e Equipment)
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Martial Melee Weapons
It's an harpoon used for catching whales. Over the years, whalers have discovered it's also very effective as a weapon to hunt other creatures.
Special. When you deal damage to a creature with a harpoon, the target must succeed on a Constitution saving throw against a DC of 10 or be harpooned. While harpooned, the target's movement speed is reduced to half and it is unable to take the Dash action.
A harpooned creature trying to cast a spell, must succeed on a Concentration check against a DC 10 or loses the spell.
A creature can remove the harpoon from its body as an action. The creature must have at least one free hand to do so. Removing the harpoon causes damage equal to the damage die of the harpoon (without modifiers).