Wel, actually, this piece is digitally colored. The lines are traditionals, but colors and effect are photoshop, so, I'm afraid there's no tool to suggest, regarding this one.

But, I easily achieve effects like these with traditional tools also. For markers, I only have a bit of experience with the Copic, a bit too expensive, if you ask me, for what they actually do, but they blend really well, and are simple to master. Otherwise, watercolor can give you all the highlights and shadows you desire, but they require a bit more practice.