|“||[Once again], immunity is back up for grabs!||”|
–Jeff Probst, before every Immunity Challenge
The Immunity Challenge is often considered the most important aspect of the game. Winning this type of challenge will secure a tribe or an individual safety from the following Tribal Council.
In rare cases, there are double eliminations where both tribes go to Tribal Council, where the Immunity Idol is temporarily retired and is replaced with the Immunity Necklace which is usually only available post-merge. After this double elimination, the tribal Immunity Idol is back in play until the merge.
In Survivor: Fiji, the first post-merge Immunity Challenge involved the castaways being divided into two teams, and as such the tribal immunity format was used with the winners of the challenge being abstained from Tribal Council.
Giving Tribal Immunity Away
To date, there have been two instances when a tribe has given up tribal immunity after winning an Immunity Challenge. In order for a tribe to do so, every member of the tribe must agree.
- In Survivor: Fiji, Jeff Probst announced that if the winning tribe, Moto, wanted to keep their luxurious campsite, they must sacrifice immunity to Ravu, which they did.
- In Survivor: One World, the Manono tribe went to Tribal Council after winning immunity to vote out Bill Posley, thus granting Salani exemption.
After the merge, where there is only one existing tribe, the remaining contestants compete in individual challenges to seek possession of the Immunity Necklace, which guarantees safety at Tribal Council for its bearer. Unlike the tribal Immunity Idol, which gives exemption to an entire tribe, the incumbent wearer of the necklaces still must attend Tribal Council and cast a vote, but that player cannot be voted out. Since Survivor: Marquesas, individual immunity has become transferable, giving safety to its new wearer, while leaving the original winner vulnerable.
On some occasions, individual immunity has been played for during the pre-merge stages of the game, usually occurring during a Double Tribal Council. It can work in various ways:
- An individual Immunity Necklace appears at a certain location on the island. The first members of each tribe to get to them are granted individual immunity in some form (Palau, Micronesia, Gabon).
- Members of both tribes compete simultaneously for a shot at winning individual immunity (Gabon, Heroes vs. Villains, Nicaragua).
- One tribe wins a reward, and the members of that winning tribe then compete for individual immunity (Vanuatu, Guatemala).
- One tribe wins a reward during a Double Tribal Council. As part of their reward, they are able to give individual immunity in some form to a member of the tribe who goes second (Palau, Cook Islands).
- In Vanuatu, Guatemala, and Gabon, as only one castaway won individual immunity at a Double Tribal Council, they would grant individual immunity to a member of the other tribe.
There has been one case where no one post-merge has come to Tribal Council with immunity. During Survivor: Pearl Islands, the jury won the Day 37 Immunity Challenge, resulting in no one having immunity. Darrah was voted out unanimously.
During the pre-merge stage of the game, tribes that are allowed to sit out members may opt to let a weaker tribe member compete for the Reward Challenge, and reserve their stronger tribe members for the Immunity Challenge to potentially better their chances of winning the latter to escape Tribal Council. Conversely, a majority alliance within a tribe may choose to purposefully lose an Immunity Challenge to eliminate an undesirable tribe member, as seen in Africa, Thailand, Pearl Islands, Cook Islands, China, Redemption Island, and Worlds Apart.
In rare, extreme cases like in One World, the Manono tribe, who had won the Immunity Challenge, forfeited immunity at the last minute and sent themselves to Tribal Council to vote out Bill Posley. In Caramoan, the Bikal tribe deliberately forfeited the Immunity Challenge before it started to oust Brandon Hantz, who was seen as a threat to the tribe's well-being, on the spot.
After the fourth Immunity Challenge in Survivor: Fiji, the winning tribe, Moto was given the option to keep their luxurious campsite, but they would have to give up their immunity to the rival Ravu tribe and send themselves to Tribal Council, which they did.
- Colby Donaldson, Tom Westman, Terry Deitz, Ozzy Lusth, Mike Holloway, and Brad Culpepper have each won the most individual immunities in a single season, at five.