Spheres of Power is a completely independent magic system that may be used alongside or may completely replace the core Pathfinder spell system.
Like spells, the spheres grant a magic-user the ability to accomplish great things that would otherwise be impossible. Bending fire, summoning angels, layering enchantments on an unsuspecting creature’s mind: all of this and more is possible for a master of the spheres.
Like spells, spheres require levels in a magic-using class. Using a sphere ability with a casting time of a move action or greater provokes an attack of opportunity (unless cast defensively), requires a concentration check in difficult situations, ceases to function in an antimagic field, and is subject to spell resistance if it directly targets an individual. Unlike spells, however, a caster may take multiple casting classes without necessarily dividing his power; caster levels, talents, and spell points gained from multiple magic-using classes all stack with each other.
Where the core Pathfinder magic system grants access to spells and spell levels, magic users using the Spheres of Power system (referred to as ‘casters’) use spheres and talents. There are 22 main spheres contained on this site, including Alteration, Blood, Conjuration, Creation, Dark, Death, Destruction, Divination, Enhancement, Fallen Fey, Fate, Illusion, Life, Light, Mind, Nature, Protection, Telekinesis, Time, War, Warp, and Weather. Blood and Fallen Fey were originally created as optional, additional spheres, but are included in this book.
Spheres provide a caster with a broad magical focus; for example, powers that deal with moving objects through space are contained in the Telekinesis sphere, while powers that deal with manipulating winds and rain are contained in the Weather sphere. Most spheres provide the caster with an at-will ability, which may be further refined through gaining talents associated with that sphere. Beyond the spheres themselves, there are several terms that must be explained for use with this system: Magic Talents, Caster Level, Casting Ability Modifier, Casting Time, Distances, Spell Points, Saving Throw Difficulty Class, and Magic Skill Bonus and Magic Skill Defense.