Out of not being able to find a suitable brush set for smooth blending, I decided to make my own. The brushes are best suited to layering.
The markers have a slight streakiness to them, suited best for layering techniques. As well as blending nicely, they also color/fill well.
The Blendy Marker has a smoother transision, with a slight transparency difference with light pressure from the Flat marker
The Flat marker is a bit more dense than the Blendy marker. making it eaiser to cell shade.
Blendable Marker Pack