Android v4.4.2
I keep running into the same problem on my tablet. The game works
fine at first, but eventually I’ll see the following when I try to retreat:
I call it the BSOD because whenever this happens, i.e, every time I play long enough to encounter it,
the game will stop responding shortly after, forcing me to shut down Gems of War and restart.
The game also crashes from time to time on Steam (not especially when retreating). I believe it is a 1.0.8 issue and devs are well aware of it.
Hope this will get fixed in 1.0.9 
I’ve passed this onto the team. Any extra information you can think of just post it here.
Well, for what it’s worth, the problem persists even after I deleted and reinstalled the game.
I also discovered that it isn’t limited to the retreat option, but when you select a troop/enemy as well:
