Rules of Magic
Spells
Each spell consists of two kinds components: the type and effects. Each spell is only of a single type, but can have several effects. Spells need to be created before they can be used; IE, their type and effects need to be defined beforehand. It takes one in-game day to create a spell, and a character can have up to their ranks in Arcana number of spells at any time. If a character wants to make a new spell, an old one must be forgotten.
Creation
Characters can only create spells from components that they know, and components can only be taught through an in-game interaction. For example, a character may happen upon a spell book that contains a Barrier spell with an increased range effect. The character can now create Barrier spells, or create other spells with the range effect.