The age of the soul has a distinct effect on the power of it. Assuming nothing has weakened the soul, it gets stronger the longer it is in a body and weaker the longer it is out. A prime aged soul is usually around 13-16 in power.

The primary patronized species of any given god give a 16 in that sphere at their prime age.

Living souls and elementals can be used, but it is incredibly risky. The difficulty on accepting them ranges 16+ and the resisting is +6 to their will, since the medium accepted them in the first place. Tapping them is easier, though, ranging from 7 to 10. Because living souls are souls made flesh, when they die, they never become undead. Thus, they can only be used while alive, hence the difficulty. Similarly, elementals have souls, but they are purely elemental, and thus, when they die, they are immune to undeath. However, they are so powerfully physical, they are close to being metaphysical. Thus, they can be used in life, though it is very difficult.

Multiple sphered species are those that are patronized by a deity that did not make the original of that race. For instance, a Dwonnic elf would give both darkness (for its patron) and life (because the original elves were made by the Silver Mother). A pearl dragon would give peace (for its patron) and dragon (for the original) and so on.

Some beings will give even more than that--all animalmen give fauna, regardless if their over race is faunal. So bipedal unguloid animalmen give war, fauna, and their sphere. Aquatic animalmen give water, fauna, and their sphere. And so on.