Okay, thanks for the question. I thought I knew the answer to this but turns out this situation is not on the Survivor tiebreaker wikia page (
http://survivor.wikia.com/wiki/Tiebreaker , it's an interesting read).
Anyway, for this game I'll construct the rule that I think is the most fair. So in the situation where all the people who got votes play their idols (e.g. Person A and Person B both got 3 votes each but both of them played an idol, making the vote 0-0), there will be a revote conducted in which everyone on the tribe can vote, but CANNOT vote for the people who played idols. Additionally, NO ONE who didn't play their idol in the original vote can play their idol in a revote, so you will be completely vulnerable. Now, if this vote ties again (2-2), it will follow the same rules as Survivor (another revote in which only the people involved in the tie can be voted for). Now, if this vote ties again (1-1), we go to the infamous purple rock, unless only one person is eligible to be eliminated since the people involved in the tie are immune to the purple rock. In this very special case, we will do a "fire-making challenge" between the two people who were voted for.
NOW, in the situation where EVERYONE plays an idol, we go to purple rock right away and everyone is eligible to be eliminated.
And of course, once we're in merge and the individual immunity necklace is in play, the wearer of the necklace is never eligible to be eliminated in any of these situations, even in purple rock.
