This is in the Known Issues thread:
- Triggering a secret that was created from another card can cause the client to freeze (Chameleos, Shifting Scroll).
When that happens to you, you can force quit the game (such as with Alt+F4 in Windows) and log back in to return to the game in progress. In a game against a human opponent, you should do so quickly to avoid loosing your turn as time continues to count down on the server.