OK, I'll post it, when the render is ready. I hope you won't be disappointed, because I didn't really know what I was doing. This node stuff is really a little bit too abstract for me. I like to work intentionally, and that's what I did. I added a bit of this and a bit of that, deleted something, and in the end I had something, but I don't know exactly how.
First I used different power fractals with different scales in the terrain tab. One of them with a stretched noise. I also used a crater shader with negative displacement to get the tower shape. I moved it below the other displacements to make it more irregular. I then wanted to distort only the "tower" a little more, so I created a new surface layer, made it completely red to distinguish it from the other shaders. I used a distribution shader and a distance shader to modify only the tower with a little bit of twist and shear and strata shaders. I then moved this shader below the others, so the displacement remained but the (kind of override) red colour wasn't visible anymore.
When I was adding the first fake stones shader I accidentally typed in a ridiculously high value, which gave me another nice deformation and colorization right in front of the tower.
For the colours I use a power fractal image function additionally to the colour itself most of the time. Usually I start with a grey surface layer, then I add a more brownish layer with less coverage, and then I add whatever fits my needs.
Adding plants wasn't very difficult. The generous people in this friendly forum provide us with everything we need. Thank you all!!!
I hope that I can contribute something in the future.
