Spirits are incorporeal, immortal beings that originate from the Spirit Realm. The majority of spirits once lived as mortals, and later ascended through Death or Enlightenment. Because of this, many spirits have particular ties to the Mortal Realm. Only a few ancient entities were born as spirits: from Pangu and the Cosmic Egg.
The nature of spirits may vary greatly. They can personify all sorts of aspects found in the Mortal Realm, as well as those that cannot be found there. Spirits have been known to pass into the Mortal Realm on occasion. This may occur in rare, harmonic moments when the two Realms converge. It can also be forced with powerful magic, to summon Spirits or even banish them into the Mortal Realm.