Upon activation, the device fires out a beam of black energy, which connects with the chest of the target creature, and forming a constant connection between the device and the creature for the duration of the effect.   Upon making connection with the creature and at the beginning of each of the creature's turns during the effect, the creature must make a CON saving throw. Upon a failure, they take 4d6 necrotic damage. Upon a success, they take half as much.   If the creature makes three successful saving throws, the effect ends early.   You may use the action on your turn to switch the target of the black beam of energy to another creature within range.