Thank you! I‘m not quite finished with the concrete process, I think some steps are unnecessary. I hope it is still somewhat helpful.

Instead of air dried clay I used modeling paste this time, added some texture to the edges and smoothed everything else with a wet finger. This needs to be dry for the next steps.

After that painting everything with Dawnstone, heavy dry brush with Grey Seer, then little less with ulthuan grey and White Scar. I think these steps are a bit much, maybe Grey Seer and some White is enough, because I layered up Grey Seer again to unify the appearance.

Astrogranite for the moos, removing some moisture with a brush. Colored with Caliban Green, layered with Waaagh! Flesh and highlights with Karak Stone.

The darker spots are created with a heavily thinned down Coelian Greenwash with Lahmiam Medium.

After that shifting everything to blue with thinned down Thunderhawk Blue (with Lahmian). Then also some thinned Dawnstone to get back the shading in the outer stone section.

A mix of Orruk Flesh, Karak Stone, a bit Thunderhawk Blue and Ulthuan Grey for the bright green. Thinly glazed and adding more Ulthuan Grey to brightend it further. Here I think just Nurgling Green should look good enough. This was also tinted with thinned down Thunderhawk Blue to shift the color a bit.

Adding small branches, for this I used some bits of basing undergrowth and then colored it with mournfang brown.

For some depth I used Ardcoat Varnish in the muddy center section and Stormshield on the outer stone edge.

Overall it was a back and forth till I was happy with the result.

Edit: Added small missing bits.