The game had some random crashed along the line but very few. Now I'm at Ark Moor (last level?) in the light campaign and regardless whether I use Direct3D or OpenGL in the config it crashes constantly which is especcially frustrating since the level is quite hard and it's happening so fast that it wouldn't even be possible to finish this level in a speedrun.

Any ideas? Is it only happening in the Linux/Wine package or a problem of the game itself?

Have you tried different resolutions?