>>107586591The Power of Shazam! by Jerry Ordway, people didn't build on a lot of the concept he build though (Mr. Finish? Chain Lightning? Ha!).
If you are done with that book, move on to the Golden Age Fawcett books and Shazam! The Monster Society of Evil by Bone creator Jeff Smith.
If you're interested in team books you could read his interactions with the JSA in the 90's JSA run.
Can't say a lot about the current run though.
