Festerwood Claymore

This heavy, dark wood is incredibly strong and forms part of the symbiotic relationship it shares with destructive beetles that live inside. You gain a +1 bonus to attack and damage rolls made with this magic weapon. When you roll a 20 on an attack roll made with this weapon against a creature, some of the sword’s beetles leave the weapon and latch onto the target. The beetles bite and hinder the creature for its next 1d4 turns. While affected by the beetles in this way, the creature takes 1d6 piercing damage at the start of each of its turns and its movement speed is halved. A creature can use an action to swat away and remove the beetles to end the effect early. If the target is a plant creature or magical plant, this property deals the maximum damage to it on each of its turns and lasts for 4 turns unless ended early by a creature.