Death

Death is the end of life, defined on Earth as the complete termination of brain activity. It seems that in reality it is (also) the departure of the soul from the body, to the world of the dead. The souls are ferried by winged Thanatos-like beings. Death seems to be personified by a deity named Prekt, though this deity's name is only used in the term "Prekt's Realm," which refers to either the Luminous Netherworld or the world of the dead

Instances
Max died in Book 1, but Khi brought him back to life, seeing a boy with wings and a sword carrying his soul to a pair of Carved Gates before he snatched his soul back and put it back into his body.