What do you think about an oportunity for gaining some superpowers in game ? 
  
Im thinking in general something of plot related or complatly optional. 
  
For exampe a mad scientist kidnap you and is making some horrible experiments and you become undead, half-demon etc ... 
  
Or mayby in visiting a old mantion a Vampire bites you and you become vampire yourself ... 
  
Or maybe even you make some secret ritual and became a  Lich ? ... 
  
  
  
What do you think ?