The Rebirth system is the repetitive gameplay process of Infinity Blade II. It is the equivalent of the Bloodlines of Infinity Blade I. After unlocking a seal or being killed by a blood sentinel, Thane, or Raidriar, Siris "dies" and a new Rebirth begins.
A cycle is a period of at least five Rebirths that spans the events between the introduction at Saydhi's Estate and the defeat of Raidriar in the same place. When one cycle is finished, the player begins a new one starting at Saydhi's Estate. In NewGame+, cycles are known as "New Games".