Thanks, @blanchsb! The stone texture is made from procedural “Cloud” texture and the damage is actually a hole visible in Vadim’s @harbinger_ua artwork. I’ll try to add some more damage but this will make some changes in the low-poly mesh necessary if it’s deeper holes, especially those which affect the silhouette. It’s tedious work because the number of stones rises with the widenening towards the bottom so that I can’t simply use a cuboid with lattice deformation. But I think that it will pay off in terms of realism. Today I had a lot of work with smoothing edges:
1) Before

2) After

Now, I’m working down the chimney again adding dents and cracks and more roughness in areas where I had to smoothen the edges. Here the top of the chimney:

Some corrections to the lowpoly mesh will be necessary because the angle of some faces has slightly changed during the edge smoothing.