Metamagic

Metamagic is the system which provides the mechanics for building magical genres, and serves as a governing or balancing ruleset. It can be broken down into two general areas of functionality: the tapping (acquisition) of Mana from Loci, and the focussing of Mana through one or more Foci to achieve a desired effect.

Tapping: Using Loci

Tapping is the generic term for some action which results in the channelling of Mana from one or more Loci into an array of Foci.

[TO DO: Add varying methods of tapping; nodes and ley lines]

Focusing: Using Foci

A mana stream by itself is just potential energy, which if not directed, will just dissipate with little or no effect on its surroundings. In order to cause some effect to occur, it must be acted on by at least one Focus.

There are three basic kinds of Foci:

• Filter - Transforms mana into some other kind of energy; e.g., heat, light, sound, etc.
• Machinery - transforms energy into events
• Lens - Controls a stream of mana energy; e.g., split, store, delay, decay, route, etc.

Magical Laws

There are also combinatorial factors that can affect the efficacy and outcome of configurations of Foci. These are laws which specify interactions between various kinds of loci and foci which can either enhance or diminish a desired effect. A few possible ones (adapted from <cite>Effective Thaumaturgy</cite>) might be:

The Law of Association

Loci and Foci with things in common interact more efficiently through their similarities.

The Law of Similarity

A Locus or Focus which is similar to another Locus or Focus can be used as a proxy for the original. The higher the degree of similarity, the more effective is the proxy.

The Law of Contagion

Loci or Foci in physical or metaphysical contact with each other continue to interact after separation.

The Law of Names

Knowing the true name of a Locus or Focus gives one complete control over it.

— GedTheGreysHain - 14 Jun 2003