Been interested in looking up alternate magic rules for Pathfinder, and my attention drifted back to one of my old books, Advanced d20 Magic by Guardians of Order, intended both for BESM d20 and the classic d20 system. It holds complete rules for skill-based magic mechanics, guidelines on how to convert traditional d20 spells to work with this system, as well as a conversion to the Magic Item system along those lines.
The Book also includes conversions to use the system with standard d20 classes, although those were controversial as being badly designed; such as the Druid being able to cast spells in animal form without the Natural Spell feat, for instance.
Still, I'm curious about the system's potential, and was interesting in adapting it to work with Pathfinder.
I never got a chance to use it in my games, but I have fond memories of Advanced d20 Magic, as I recall it being one of the most free-form d20 magic systems in terms of what you could do with the actual casting of the spell (albeit not with spells themselves).
I love the system. It was originally presented in d20 Slayers to represent the magic used in the Slayers setting. When I saw it then, I knew just had to find a way to make it work for my games. And when GoO came out with Advanced d20 Magic, I just knew fate was on my side. All the work I would have had to do to the 3.5 core spells was done for me. I got the book, but to this day, I've yet to use it. A Pathfinder conversion would really make my day.
I bought the book a while ago. I think it's a good alternative to the crappy spell-slot system which has plagued D&D/Pathfinder from the beginning. However, it was a bit over-complicated in that the cost for each spell was rated individually rather than by level. I assumed that this was because they'd reverse-engineered each spell to come up with a point value for it based on GoO's flagship game Big Eyes Small Mouth (BESM) and then calculated the casting cost from that. It would be easier, but perhaps less accurate, to cost spells simply by casting level. I'm thinking of offering the players in my current Pathfinder game the options of Advanced d20 Magic or the Words of Power system in Ultimate Magic.