Apotheosis is the process of transferring one's consciousness to an inanimate object, such as a robot or a frying pan. This process was well-known and used by the Starlings and Pyreans. Apotheosis is reversible, if the original body of the user is kept intact.
Joining one's consciousness with an inanimate being grants immortality and protection from The Cleansing, as only living organic beings are affected by it.
The most well-known use of Apotheosis is The Black Guardian, an ancient tinkerer who joined his consciousness with his own robot before it was able to move thousands of cycle iterations ago, and so is trapped forever underground watching as The Cycle unfolds and iterates again and again. The Pyreans also knew of the process, and used it to join a consciousness with a temple, creating The Living Temple. Yerai Dal'Terrowin, a Starling, has also mastered Apotheosis and has presumably transferred himself to his Centurion, Horst.