This Brush Tip was used on a Pen Tool. It works great to make clouds with and sort of smokey looking effects. Try it out, I was surprised at how easy it made making clouds!
In order to make the clouds, you want to make verticle brush strokes. The lighter you hold your pen, the Thinner the effect. So you want to press a little harder towards the center of the cloud and let go more towards the end. Test this out and using different shades of whatever color using for a great manga styled cloud!
-Aoshika