Now, on to this season's twist!
This season's twist is called the "Secret Savior" twist. After each immunity challenge, the members of the winning tribe will be mailed a simple, non-live, low-effort challenge to complete (spam, a flash game, trivia, something like that). Whoever wins that challenge will become the "Secret Savior" for that round, and will be able to anonymously give immunity to one person on the losing tribe.
The catch is that this functions in the same way a hidden immunity idol does -- it will not be revealed until after the votes have been cast who the savior decided to save, meaning any votes cast for whoever was saved wouldn't count.
More specifics on this will follow when you compete to become the Secret Savior.