The Price of Magic

There's an interesting trope in many fantasy films and many works of fiction.  Often, if there are two mages or wise men who are leading (or mentoring those who lead) competing sides of a conflict, the one we would identify as good is typically much older and more feeble looking than the one we would identify as evil, who often looks like they are in their prime.  Professor X and Magneto.  Obi Wan and Darth Vader (or Yoda and Palpatine).  Dumbledore and Snape (or Malfoy or even Voldemort).  Egg Shen and Lo Pan.  The urRu and the Skeksis.  Most martial arts movies that involve a rival dojo do this, like Mr. Miyagi and John Kreese (The Cobra Kai sensei).  I'm certain I could find other examples.

Why is that?

What if there’s a reason that all the good wizards look so aged and the bad guys look like they are in the prime of their lives for the most part? What if there was a cost to magic, aside form whatever material components are associated with a given spell? What if that cost was life force measured in time?

We all have a finite amount of time in the world – most human beings might live a century if they are very lucky. Elves on the other hand, have lifespans measured in thousands of years, at least in most systems.  What if this is why they are typically depicted as if they are naturally more powerful, facile, or skillful than human mages? They have more life force to “burn."

What about the evil mage? Why do they usually look more vital?  Is there a way to cheat the system? Is this what draws some people to evil in the first place? That they don’t want to give up their own life force so they use the life force of others?  This gives us a rationale for all those sacrificial rituals, and explains why it usually involves the sacrifice of someone young.  Perhaps this is what ritual magic is all about, harvesting the life force of the victim for use in further magical rituals.  This also seems like a natural way to divide white and black magic.

I have never really played with age in my campaigns, but it might be worth introducing.  This could also serve as a way to keep fighter classes relevant as the players enter higher levels of play - sure, the mage can whip out Incendiary Cloud but does he want to do it if it is going to cost him a decade of his life?

There are a number of items (Potions of Longevity, etc.) that become much more relevant with this system in place.  It also makes perusal of eternal life ala the Lich make a little more sense.

It's possible someone has tried something like this already - if so, I'd love to hear about it!  Here are some proposed costs for spells in D&D – each casting of such a spell ages the caster by the amount listed UNLESS they use the life force of another....