Dastardly Dilemma is a twist that debuted in Survivor: Kiribati. It forces three people into a decision where they can either secure their own personal game, or forsake it for the good of the team.
One of the three people placed in the dilemma can, by simply stepping forward, immune themselves for the next three tribals they attend. However this comes at the cost of forsaking the other two people caught in the dilemma, as taking immunity will force the other two castaways to be unable to vote for the next three tribals they attend. It's a selfish prospect, but one which comes with a huge advantage if you are scared for your position in the game. Alternatively, none of the group can take this option, and keep their votes and their vulnerability. Yet they may regret this decision later down the line if they run into trouble.
In Kiribati, Christian, Jasper and Nick were forced into the dilemma after they were unpicked to be on a tribe at the tribe swap by random draw, and therefore forced to attend Tribal Council by joining the losing tribe of the immunity challenge. However ultimately, all three stuck to their guns and did not take the advantage.