From the Introduction:
It was not so long ago that soul magic did not exist. Before the darkness arrived no one had heard of it, instead magic was gifted by gods to their followers. However shortly after the arrival of the darkness the gods seemed to turn their backs on their followers and their powers dwindled to nothing. Once the majority of the priestly magic had left the world the soul magic appeared from an unknown source.
Practitioners of this magic believe that their souls are directly linked to the world and through the world they are linked to the lives of everything and everyone. They believe that by drawing on the soul, they are drawing power in essence from the world and life itself in order to cast their spells. Soul magic, when compared to mage magic, is more limited as mages get more spells and are individually more powerful. However the benefit of soul magic is that two or more low level soul casters can "join" in casting a spell to gain a high-powered effect.
There are three types of Soul Casters:
Light Soul Magic
Light Soul Magic revolves around life and purity. Light soul casters cannot join with dark soul casters when trying to cast a spell to greater effect; they may only join with other light casters.
Dark Soul Magic
Dark Soul Magic revolves around corruption and death. Dark soul casters cannot join with light soul casters when trying to cast a spell to greater effect. They may only join with other dark casters.
Grey Soul Casters
Grey Soul Casters walk a fine line between life and death. They have a very balanced outlook on everything that they do, never favouring one or the other. You cannot become a grey caster; instead you must choose to be one when you create your character.
Unlike mages, the soul casters do not have to learn spells. Instead, when they reach a certain level of power, they gain all the standard powers that go with that level. There are rumours of additional powers that they may learn at higher levels but it is still a new type of magic and few, if any, have achieved a high level of mastery in it. The benefit of soul magic over mage magic is that soul casters can "join" when casting a spell. For example, if two second level casters joined to cast a spell they could duplicate the effect of a fourth level power that neither could cast alone.