The only time I've used layering effects is with my map creation, though it was amazing to see unfold. Hopefully I'll get into it enough to start implementing other ways. I took a look at your graphic novel, really great site setup and story!
Thanks . Try setting your brush effect to one of the layering effects as well, it will act differently if it is used on a flat background compared to if you draw on an opaque layer. Best to make a top layer containing a flattened image of your work and play with that, can get some really great results.
This is really good. You should try getting in business with authors or publishers, some of these would make for great novel covers, especially the second one with the lightning.