There's no place on earth that's "zero" mana, and while paracritters whose Magic is reduced to 0 lose access to their paranormal powers, they are not otherwise injured or limited.
This got me thinking a whole bunch of questions (that I could not find in the forum search function).
1. there used to be rules for those dumb enough to look in the astral or try magic in a suborbital. What is the deal with this now?
2. what is the deal on Mars?
3. is it possible to trap mana in a mana barrier to maintain some magic outside of the atmosphere?
Personally I liked the idea of each planet in the solar system having their own astral presence as a metaplane and that the Horrors are actually from the outer planets.
That the cycle of magic was based on some Solar cycle and as mana increased the void between the planets would start to create bridges between planets when planet's orbits start to go in sync.
BTW: Did anyone see this article on trying to live on Venus?
http://www.space.com/businesstechnology/08...cloud-city.html