Astrological laws govern the ebb and flow of Sekhem through a mummy’s remains. This process is called the Sothic Wheel, named for the 1,461-year movement of the star Sothis (Sirius). At each turn of the wheel — each Sothic Turn — the star appears at the first dawn of the ancient Egyptian year. The historical dynasties associated Sirius with the goddess Isis, the mother of magic and wife to Osiris. The Shan'iatu incorporated these celestial energies into the Rite of Return, though these dynamics are tied to the day of the Arisen’s first death, rather than to Sirius. Nevertheless, the sorcerer-priests appear to have created most of the Arisen on or within a century or so of Sirius’ natural cycle.
A mummy arises automatically due to the arrival of his personal Sothic Turn. During this time, he is without a direct mandate and is free to pursue his own agendas. This makes it very confusing for the Arisen, who normally return with a clear purpose on why they returned. After their Memory returns, the Arisen is forced to spend his time in one way or the other. Some make researches into their own nature, possibly finding evidence of Apotheosis, while others expand their Cults (or build a new one, if their old one was eradicated during the ages and the mummy awakens in a museum). Sekhem depletes more slowly during a Sothic Turn, and many Mummies quickly search for a purpose- be it protecting their cults or tracking a Relic.