The Change is first mentioned in The Warlock. It is a process that is seen to affect all Great Elders and some of the Elders when they come to be of a great age. It changes their appearance in some way, which Abraham is mentioned to believed to reflect their true self.
According to Prometheus, some transform into monsters, sprouting furs and fangs; others became hybrid creatures, growing wings or fins on their bodies. Some shrank, while others grew monstrously tall. Many went mad.
- Abraham: His skin turned to gold over decades.
- Areop-Enap: She was transformed into a giant spider and took great offense when Abraham said that the Change is a reflection of her true self.
- Anubis: Began looking like the Anpu and other human hybrids he created in his labs underneath the Pyramid of the Sun.
- Ard-Greimne: His face paled, and his skull elongated.
- Aten: His head and lips began to elongate, while his eyes sunk into his face.
- Bastet: Face and hands turned into a cat head and cat paws and she also took great offense when Abraham said that the Change is a reflection of her true self.
- Echidna: She grew a serpentine tail, draconic wings and her hair transformed into a writhing mass of living, venomous snakes.
- Hekate: Daily morphed between a young maiden, a grown woman, and an old woman. Only her mid-day self (a grown woman) remembered all the encounters she'd had as all aspects of herself.
- Inanna: Received the wings and the feet of a bird. It is likely, but not official, that her bones have lost most of their former weight as well and her muscles are now stronger as a side effect of being able to fly with wings.
- Janus: Gained four completely different faces, each one capable of talking independently.
- Nereus: The Change gave him octopus-like tentacles instead of legs, making it difficult for him to walk on dry land.
- Quetzalcoatl: The Change gave him a feathery tail, and a hawk-like nose and a face that can change into a monstrous mask as well as an extremely elongated black, forked tongue he could use to strike out with.
- Xolotl: The Change made him skeletal, and gave him a dog's head.
- (Though not proven, Mars Ultor's undying rage could have been affected by the Change)
- Mars Ultor hasn't been mentioned being affected by the Change. However, he was mentioned having a black forked tongue and vampiric fangs, which may be his Change. However, it is also very possible that his distortion is a result of the Four Swords of Power.
- In the series, there is much contradiction about the Change. It originally was said to not have affected the Elders, only Great Elders. However, once that was altered, the change visibly affects Ard-Gremimne, while it hasn't affected Zephaniah or Prometheus, who are both most likely older than him, and might even be his mother and uncle. It has also not mentioned to have affected visibly Benzaiten, who is almost surely a Great Elder, as Sophie finds within the witch's memories in The Sorceress, though it was stated she is physically small (a possible effect of the Change).
- Isis and Osiris were not affected by the change as they were not Elders, but Earthlords.
- The Change has not visibly affected Zephaniah, Prometheus, and Odin, despite the fact that they are of a similar age as Bastet and Hekate, and even older than Anubis, Ard-Greimne, Aten, and Hel.