Here's a quick run down of how I make rocks. I was in a bit of a hurry so its not exactly how I do it but its near enough and gets the same visual effect. Im sure people can make it neater by putting some brushes into one single brush, and keeping as many faces perpendicular to the floor as possible (both of which I do normally but I was hurrying).

1. Make your ground and various blocks along the place you want your cliff. Select all of these blocks at once and go into vertex manipulation mode. Drag selection boxes over each front vertex [there are actually a few of them under each so if you just click on them you will have to move each twice] and move them about to make a basic outline as below.


If you are struggling to keep r_speeds down then you can just stretch this basic shape up to the sky, which I did in most of my maps such as CM Arena. If your only using them sparsely though, continue on...

2. Clone the base and place it above, by holding down shift as you drag the shape up.


3. Click on this twice to change to the third mode of the selection tool. I dont know what its called but it moves faces and ive found it to be very useful recently. On the side view use the top handle on the shape and move it. It will become obvious what it does once you give it a shot.


4. If you've got the r's to spare then you can repeat this again to get more interesting cliffs.


Thats a basic tutorial on how I do my cliff faces, hope it helps you out If you have questions then either email me, post on the forums, or leave a comment on this tutorial.