The manipulation of the Ground Plane causes a massive problem with non parallel faces and I don’t rely understand what to do about it. 
If I try to scale along a planes normal (local z) with 0 it fixes that face but every other face it has contact with turns non planar. How should I do?
I have googled around a bit, although perhaps not as much as I should before asking in the forum so please have mercy if I come with an unworthy question 
but it’s late you know and I’m getting rely tiered. Also I have a feeling that maybe it is not so important because the instructor do not seam to care. Maybe I’m overambitious?
P.S I found it to be virtual impossible to get the Knight truly planar. I used the modifier trick to hide the triangles on the rendering. But it would be nice to know how to get the faces truly planar. The manual methods that I found with google seamed quite horrifying concerning workload. Any tips on addons or something? 