Wow!! If you are right, I've been playing the game wrong for a very long time. As far as I know, without the book at the office, the Power level of a spell is only against the Power of the caster. A Chasm is 5, against the Lotus Eater's 15?, so the cast is a 10, or a 9 if the Power is 14. You get the idea.
If saving is as difficult as you say, I'm'a load up on casters....
Steve, let me know what page you're on in the book so I can check late late late tonight and see.
Cheers.