Mignola master study

I decided to spend some time studying Mike Mignola's work (Hellboy) to try and wrap my head around how he does it. On the outside his work looks so simple... elementary school simple but it really isn't. The more I try my hand at duplicating his styling the more I am struck by how his mind might be working. Most of us use one light source... he appears to use three. And then sometimes he breaks the rules of the light source and spot blacks in a place that he shouldn't but he does it in a way that it works and you forgive him for breaking said rule. There actually is genius at work with him.

Mikes work on the left and my interpretation on the right.