Sprinter mob

This ghostly enemy hides in the dark and will indicate when it spots you. It will then rush towards you and deal damage if it is not blocked by a shield or attacked. Upon attacking the player once or being blocked it would disappear. Not the strongest mob but could be a threat in certain situations. It is stationary when not attacking the player. If the player is further away it will stare at them, like eyes in the dark, but is virtually invisible when they are closer but not close enough to attack. Maybe its eyes could be white to be a fakeout of herobrine.