Quick update – I blocked in the cracks & crevices in the rocky base with black, and then went back over the raised areas with some dark grey. I then carefully went along all the edges where the flesh meets the rock and feathered in a nice blend. This was particularly tricky between her legs!

I then tinted the rock and rock/flesh blend with some fairly random overspray of transparent purple ink to try and replicate the colour of the rock in the original artwork.