The fists of my dire trolls all fade into green, so the large fists of the Mountain King are the perfect area to show you how I do a fade. This can probably be done with an airbrush, but I did this with a trusty old brush.
Step 1: Basecoat. I have purple trolls, hense the Daemonette Hide color.
Step 2: To start the fade effect I layer on an intermediate color. In this case, on the color wheel purple and green are separated by blue, so this intermediate layer is blue. I am using 'The Fang', which is a neutral blue. Make your paint strokes follow the contours of the muscles and skin to help them blend in.
Step 3: Now for the final color, Caliban Green. Be sure to leave some of the blue showing.
Step 4: Start layering on your highlights, starting with the main color. Here I highlight the purple skin with Warpfiend Grey. Then I highlight the blue areas with Fenrisian Grey.
Step 5: Now layer on the green highlights, being careful to leave some blue showing.