reveal? What are you talking about?) All the rules in Heroes tournaments are based on trust. It has always been like that...

If, according to this statement, everything is based on trust, then why raise the issue of joining neutral creatures?
The problem was stated, and various solutions were also proposed. And as a result, it turns out that there is no problem. Fantastic.
By the way, you can write a script that tracks illegal joining, but it is quite complex due to the lack of creature names.

Added 6 minutes later

I didn't quite understand about the rifle.

A thief comes, pulls out a knife. And there's a rifle on the wall, and it's even loaded (and the thief didn't even know it was there). Will he grab it? Or just give up the money?

I have a feeling that the leveling is going too fast, it will definitely end soon, and here's a week of creatures and the temptation to join them, but the opponent won't even see it.