Is there a way to show a PM to the world in a manner that cannot be faked? Yes, to lie about it could wreck the game and result in bad feelings, but this does not feel foolproof at all.

It’s not intended to be foolproof; that’s why I called it “honor system.” It’s just defining a legal action to take. There are many opportunities to cheat at this game if you’re playing in bad faith, but cheating has not historically been a problem.

I feel like a honor system for trading cards would likely emerge even without a rule making it explicit.

  not too sure about the private communication only, wouldn’t it be better to have public trade blogposts so that everyone can verify whether someone has agreed to a trade? the hands are open for everyone to see after all

[card] I’ve seen a lot of public trade blog post mechanics in past dynasties, and they always end up a) clogging the feed and b) being ripe for timebox conflicts (duration of an active trading post, forgotten active posts, conflict among the state of trade posts and the availability of items, etc). This is an attempt to bypass all that. As you correctly point out, the open status of hands seems like enough of a public record.

Being able to selectively invalidate actions by conspiring to pretend to have agreed on a card swap seems a bit too tricksy.

Honor is dead.

(Odium killed him)

You could still propose to have a version where public blogposts aren’t used for communication but validation and any trades expire after 24 hours or if the cards proposed for trade are not in the Wizard’s hand. If you wanted it to not clog up the blog there could just be a stickied blogpost and trades are validated in the comments.