I've got a question about these two cards because my opponent believes you can use Iron Will on Game of Sincerity but I disagreed with him. Game of Sincerity just says target an enemy and your personality and dishonor both of them and make them not contribute force during resolution+ the honor loss. My argument was it just says target a personality not choose your performing personality and target the enemy personality which would make Iron Will a legal move in my opinion. Who would be right in this situation since it can be a game changing thing?
Iron Will vs Game of Sincerity
A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
Iron Will says:
Reaction: After another player targets your Paragon with a Battle action performed by a Personality with lower Personal Honor: The action's costs are ignored and its effects are negated. That player may take an additional Battle action.
Game of Sincerity says:
Battle: Dishonor your performing unbowed Personality and target a Personality: Dishonor him. His controller loses 2 Honor. Neither Personality contributes Force in this battle's resolution
(Emphases mine) It seems that your copies of Game of Sincerity are not the Most Recent Printing (War of Honor) but come from the original printing (Imperial Gift 1). You can check both versions in the link, but the one from War of Honor is the currently legal text since it's the most recent. As you can see bolded in the quote, Game of Sincerity is a performed Battle action (Note: The old version was also performed, but the rules on performing were different back then so the wording had to be updated).
If the player A announces Game of Sincerity, chooses a performer and targets a Paragon with higher Personal Honor than the performer, that is a legal trigger for Iron Will.