What is the best way to pass the users selected deck ID from the client to an authoritative server? Assuming that both will need to submit their deck IDs then the server will have to broadcast the state with the setup of each side.
If they set their deck for matchmaking then we recommend you thread through that information from the data properties in the matchmaker into the match handler created on the server.
That way you know what each player preferred before they entered the match.
And don’t have to push it into the match handler as a “preflight” to match start.