A simple ribbon brush for drawing surface cracks. Works well for old walls or floors. Maybe you could use it to draw lightning?
This is a simple ribbon brush which uses a small number of hand-drawn cracked images to draw surface cracks. Each stroke is a single cracked line which always fades out to thinness at the end (but not the start).
Try drawing starting from the outside edge of a surface.
You can make your cracks more complicated by using the brush to draw additional cracks branching off from the first one. I find that reducing the brush size for branches works best.