I got it free in the playstore. It's a great app. The thing i don't like about it is because it only has 3 layers.

I use them layers for:

Add all the layers.

Go to the second layer.

Draw my guide. (on the media)

Go to the top layer and add the line art.

Erase everything in the second layer and do all the shading.

Use the bottom later and do for the background.

I'll show you guys later what my art would look like after a couple minutes.