Work based on concept @hw 6523 I use Houdini for generating small rocks and large rock base forms. Then move to ZBrush and sculpt from there.
asset kit
I created two sets of texture tiles for the tower texture since the tower is way too big.
I use the blur slop filter for creating a stylized stroke-like effect
You will need enough curvature to maintain a good stylized painting mask of the texture.
I use planes to mimic a partial shadow effect.
change the source angle for better soft edges of shadows.
Reference image. Awesome work by hw 6523
reference board