Complex sentence: As with the other EC comics edited by Feldstein, the stories in this comic were primarily based on Gaines reading of a large number of horror stories and using them to develop "springboards" from which he and Feldstein could launch new stories.
Split into simpler sentences: As with the other EC comics edited by Feldstein, the stories in this comic were primarily based on Gaines reading of a large number of horror stories. He used them to develop "springboards" from which he and Feldstein could launch new stories.