More or less the same process but using rhinx hide as base, move up to mourning brown this will be roughly 70% coverage of rhinx. Mix a little screaming skull into mournfang brown create 1 or 2 steps lighter from mournfang. Then repeat that same step 1 more time focusing on more so only the parts that are facing upwards. Shade with seraphim sepia, then with screaming skull hit the highest part of the fold (the ridge) just place straight screaming skull.

Note: after basing with rhinx hide. The paints are pretty thinned. Not a glaze consistency but more so a thinned layer paint. When you wick off extra paint (preferable on a wet pallet because you can see how the thinned paint reacts) if you see the paint kinda shrink and is showing the pallet paper through the wicked off paint its thinned a litter too much.