I assume you're asking for something a little more condensed than FA? 🙂 I'm going with a collection of crammable things compiled from a list of things I typically get confused. For example: acid/base disturbances; sensitivity vs specificity box, anti-mitochondrial vs anti-microsomial antibodies, viral structures, the gram+ & gram- bacteria algorithms in FA, etc.
I think your most HY review is going to be very specific to what you struggle with the most. And HY last-minute cramming is not the time for "understanding" IMO. Just do memorizable things.