Any supplemental magic system books out there?

[Xexyz]

Say, I'm wondering if anyone's written up a book with supplemental magic rules. Specifically, I'm talking about things can can alter the existing spellcasting system - not replace it. Stuff like ritual spellcasting, cooperative spellcasting, use of ley lines/nodes to power magic, that sort of thing.

[Jason Nelson]

This would not be a complete solution to your question, but you might check out The Way of Ki and Meditations of the Imperial Mystics, which among other things deal with the use of ki to manipulate or alter spellcasting in a number of ways.

[Purple Duck Games]

I would also suggest you check out Super Genius Games' offerings. They have a number of alternate magic systems including spell points, riven magic and others.

And Pact Magic by Radiance House.

[Anonymous Visitor 163 576]

The E6 rules do something along these lines,

link

[Alzrius]

There are alternate magic systems in Eclipse: The Codex Persona, as well as ways to tweak, alter, and supplement the existing magic system of Pathfinder in virtually any way you like.

Some of the more basic ways that are present in the book are spell points, body fuel (e.g. you take damage to power your spells), inherent mana (generic spell levels to power a few spells), and if you get into the book's method of corrupting and specializing spellcaster levels there's so much more: for example, on the author's blog there's a level three character who has to kill another arcane spellcaster and steal the spells they had prepared in order to replenish his magic.

[TrickyOwlbear]

Although written for OGL/d20, the Behind the Spells Compendium details the histories and variants of three dozen spells of the most basic spells. Each chapter shows at least two alternate ways of casting a specific spell and introduces new spells/magic items based on the backstory. Everything works fine with Pathfinder and, as per the OP's qualifier, can be introduced and used without changing the existing spellcasting system.

[terraleon]

Ley lines are discussed in the Midgard Setting. Incantations are covered in Zombie Sky Press' Incantations in Theory and Practice. There is a rune magic system offered in Kobold Press' Northlands (Runes) and Pirates of the Western Seas (Aboleth Glyphs).

-Ben.

[Xexyz]

Thanks for all the suggestions, everyone. I'll check some of these out when I get the chance.