I love this system & use it extensively. http://www.amazon.com/Primal-O
I puchased this back when WOTC was a role playing company & Magic the gathering hadn't turned them into the company they are today. The Primal Order was designed to eliminate two major flaws in the then-current treatment of deities in roleplaying games; either said deities were treated as all-powerful beings (leading to a great deal of difficulty if two different gods wanted different things, AND eliminating the high-heroic possibility of direct conflict between gods and mortals, cf. Conan, Greek and Norse myth, etc.), or they were basically ordinary characters with really really really high statistics (making it hard to differentiate between a god and a buff mortal).
This is another of the game books you can pry from my cold dead hand.
Review here http://www.rpg.net/news+review
If you look around there are much cheaper copies to be had.
The world-building advice and sample characters are excellent in their own right.
I look at what they published before they hit it big, and wonder how many other promising games were killed by Magic
More here The_Primal_Order
|Divine Hireling Book - Extensive Examples As Well ****|
|Planes of existence & how they can be used as both adventures locations, treasure for gods, etc. ****|
|Low Level Minion Book & More Monster Options By Nigel Finely!|
Everything in this line was excellent but then some game called Magic The Gathering came along & changed it all