1. Put "-force-d3d9 "in the launch options, without quotes!
2. Disable anti-aliasing.
3. After every battle save the game. Exit the game after saving. Try to save whenever possible.
4. Before re-launching game, verify integrity of the files.

If you do everything, you should experience no crashes. Yeah it sucks to restart the game each time , but if it works, it works! :D