Pathoma is a tremendous resource in studying for USMLE Step 1 and preparing for third year clerkships. It covers all of the high-yield pathology points. He explains everything from a basic mechanistic approach which is critical because that is how the questions are tested, but more importantly it develops true understanding which is never forgotten.
He can take the pathophysiology of any organ system and present the information in a way that makes the entire mechanism click in your head.