
(Laughs)

Nell, my dear, if I told you that, all the mystery would be sucked out of life.
Oh well, I feel like sucking. I have my straw right here.
Spirit magick is, like I said before, the summoning and focusing of spirits and their energy. It can be used for things like healing and attack, but it's most powerful ability is allowing the user to send his own spirit out to accomplish different things, the basest of these being long range communication, but can also be used to take over people's and animals' bodies. Other things Spirit magick can do: speak with spirits, read dreams, channel energy into tangible form, heal (or rather, purge of infections or demons), attack the spirits of others...other things are possible, but these are the most common.
It's kind of a mix of shamanism from Slayers (if you watch anime), and real mystic religions, like Druidism, Wicca, Native American spirit animal stuff, ect. The wolf and the falcon are common spirit animals.
Speaking of which, spirit animals are etheral energy in their natural form, at least, on this plane of existence. They bind with those who wield Spirit magick, and act as familiars and companions. Even a beginner Wielder can "ride within" their spirit animal, even if only for a short time. This ability increases in scope and range as he becomes more powerful and proficient.
Penance can't absolve your sin...Reap your life/Veiled in shadow/Recognize/Faces of the crucified/I can hear their screams tonight/Ever haunting me---- Disturbed, "Believe"