Sometimes when a person is murdered, the pain and rage they feel at the wrongness of what has been done to them lights a spark that prevents their soul from entering the River of Souls and keeps it locked on the Material Plane, transforming their body into a revenant: a single-minded murder machine existing solely to slaughter the person that killed them.
They always know the exact direction to their target, as long as they are on the same plane of existence. When a revenant encounters its murderer, it gains the benefits of a haste spell along with a +4 profane bonus on attacks, damage, grapple checks, and saving throws against their target.
They have one significant weakness: if they are ever confronted with their own reflection or an object significant to them in life, they must make a Will save to avoid becoming overwhelmed and helpless until they are attacked or they see their murderer. If it makes the save, it then reacts to that by making the presenter of the mirror or object its immediate target.
First Reference: Chapter 38
Other Notable References: —