Fighting Ol’ Toomba as the sixth, I believe, challenge for Dalaran Bank.
I had a Y’Shaarj on board with Effigy as a secret from Twisting Scroll.
Ol’ Toomba attacked Y’Shaarj with Vorpal Dagger, 1/2 at the time of swinging. Y’Shaarj died summoning a Giant Imp, but after Effigy was finished the image for Shifting Scroll appeared as played and does not leave the board.
In this state the AI still responds to taunts, but it makes no further actions and it is not even possible to concede from the options menu. Pressing Concede only closes the options menu.
Will post a screenshot of how it was for around 10 minutes before I just went ahead and force killed the Hearthstone Application. Interestingly when killing the application it does still seem like it is doing something maintaining around 15-20% CPU usage.