One who avenges or vindicates
One who takes vengeance.
An uncontrolled or unpredictable person who causes damage to their own team, faction, political party, etc.
A cannon that breaks loose from its moorings on a ship during battle or storm, which has the potential to cause serious damage to the ship and her crew.
To behave in a way such as to cause damage to one's own faction, political party, etc.