Using the watercolor pencils and blender pen is all about laying down the colors with the pencils correctly. For this image, the shading on the cat mostly comes from a thin line of black I placed on the edges after I colored the main parts of the cat in gray. The shading on the dog was done by coloring the main parts of the dog in light brown and adding an edge of a darker brown and then an even darker brown near the border. Much like you would do with any other technique.
The upside to the technique is the colors blend fast and your pencil strokes disappear once you apply the blender pen and starting moving. Another plus is the blender pen only wets the top layer of paper so you don't get wrinkled paper. The downside is it didn't take too many strokes from the blender pen before the top layer of paper was coming up even with the lightest of strokes from the pen because it was wet. I was using 110 lb white paper not watercolor paper, but that was the point because watercolor paper is even heaver and has a distinct texture. This was unexpected because the paper doesn't come up usually if you use a brush.
I eventually figured out how much blending I could do with the pen before paper started collecting on it and learned to let the top dry and go back later if I missed a spot. It also took a bit of trial and error to figure out exactly much color to put down because that determines how dark or light your final image ends up being. My first attempt ended up being so dark in the one area I didn't bother finishing it. The cat is a good example area. Put a very light line of black around the cat and you can drag it to be nice shadowing. Put too much and you get a dark gray cat. With the Copic markers and colored pencils, you blend but you can't move the color nearly as far as you can with watercolors so overcoloring doesn't have as much of an effect.
I think you can see in the final image there was nice color blending but it ended up drying a little bit splotchy. Overall the technique is quick but it takes some practice to get proficient in putting down the right amount of color. I only got one shot at blending it before I was risking damaging the paper.
Up next, once I get a card design I like for it, will be take two of the Gamsol technique. I think I figured out how to a get a Copic like image out of it instead of just coloring the edges and blending to white.