Animate GPencil With Lattices!

Blender Sensei writes:

I think there's huge potential in animating grease pencil objects with lattices and shape keys. Doing so makes it possible to animate an entire set of facial expressions that could be used interchangeably between drawings. I imagine this could be developed further and made an even simpler process. This method is not a replacement for individual frame animation, but the potential for creating (motion-graphic styled) libraries, interchangeable for all your drawings and characters is huge. I'll show you what I've figured out thus far from beginning to end in this video as we draw and animate a character from scratch.