Hearthpwn

 Theres no certain initiating trigger for the bug to emerge from, but after prolonged periods of play time one of two things will happen; the entire screen of the mac will go a rainbow colour (see image attached) or the minions picture will go the colour and shortly after the game will become unresponsive. Even after logging out and logging back into battle net the game will say "playing now" even after closing hearthstone in the task manager. Hope this helps whatever you needed the information for.