Attacking with Rallying blade into enemy Sorcerer’s Apprentice triggering enemy Duplicate secret created by Shifting Scroll locks the game. The Shifting Scroll card animation was stuck on screen and I could not get rid of it. After ending my turn, I could not see any of my opponent’s actions and I never got another turn due to being locked out.
I have two screenshots but seem unable to attach them.
This is included in the known issues topic, May 22 update.
Until this is fixed, you can work around the issue by a quick force-quit of the game (Alt-F4), restart, and then after the game reconnects you can continue.