Ok so quick status report:
I found an awesome CC-0 Rock Brush set on Blendswap that lets me sculpt insane amount of detail really quickly.

But I thought it almost looks to photoreal for the artstyle we try to achieve. So I also started sculpting the same mountain using the “Stack o Rocks” techniques and trying to get a more stylized mountain.

It is not finished yet but I am learning so much it´s awesome!
So what do you guys think with which technique should I continue?
@theluthier @adrian2301