Having issues with cycle nodes on object

Hi guys, I have a rock structure in some lava, found the node setup here http://www.blendernation.com/2015/02/28/make-lava-with-black-bodies/

I got the nodes nicely tweaked for the lava, however for the rock i used the same nodes but highly tweaked the values so its only rock and no lava, basically volcanic rock. This was using the “noise” texture.

The issue now. I want to add a cell voroni texture over it as well so the rock appears to have cracks in it. I have tried a few things but the current node setup seems to only allow one texture as it cancels out the other one if i combined them. I have tried Texture coordinates, mixing, bump mapping etc. nothing shows it up. any way to complete it? It should be able to use the current node setup so the cracks dont stand out too much. I was thinking of a color ramp to show the depth of the cracks as well maybe? Thanks.

I’d imagine adding one more layer of textures would ruin natural look of this lava since cracks from added Voronoi would be in no connection with what’s already available in image.
Here’s what can be done based on available textures.
This makes use of what is still Cycles experimental displacement feature thus is being a bit unpredictable (what’s seen on a preview can look different on render; to make sure any node changes are caught by Cycles you’d need to adjust values, jump to Solid mode and back to rendered view).
New Blender versions hopefully will have this feature fully developed, it’s in a works afaik.
Do not forget to add some Point Density smoke ;).