Diamant: Treason! Micro-Expansion

Diamant: Treason! is a micro-expansion composed of 12 cards.
All players start with 3 cards in their hands: 2 Decision cards, and now also a Treason card. Unlike other cards, the Treason card can only be played once per player and per game.
During a Decision phase, you can select a Treason card to Continue into the cave, but when you reveal it, you do it in front of another player.
If this player was Exiting the cave, he must give you the value of 10 Rubis in the process, which you add in your Chest.
If this player was NOT Exiting the cave, then nothing happens.