I usually do a pre-emptive restart of the game before I go into GAC or TW to do my attacks. If you watch anyone that streams GAC on twitch or youtube, you'll notice that they often do the same thing. I have no idea if this helps as I still occasionally get crashes and I don't always remember to restart before doing my battles - but it's become something of a ritual.
It's annoying and frustrating but as Magruffin said, it's a known issue with the game and all we can do is try to work around it and shrug it off when it happens. I would love for CG to fix this, but we've been waiting for that for a long time and they've only made limited progress with reducing game crashes, in spite of their efforts.