For the Doctor's first phase; Keep your distance, not too far, not too close, hit him with some bullets and then jump out of the way of his red streams so you don't get hurt or die. And when he's in the air in a closed-in position, run to a corner and dodge the hoard of streams, don't attack the Doctor at that time or you'll most likely get hit. On his second phase same thing, keep distance, hit, jump, repeat, when he's about to fire his hoard of bats; have the blade at level 2 and spam it on him to destroy as many bats as you can while hitting the Muscle Doctor, this can help save you from some damage later on. On the core battle, I recommend hitting the Core first, the moment it closes after its first set of hits spam the living heck out of that blade out on Misery, once she's defeated just dodge mutated Sue, and hit the Core with your blade or machine gun. After that, just repeat until you win. Once outside, go for the Prefab house and there yah go, you can save and go into Hell. Just don't die. And clearly everyone has already given you advice on Misery so just use that with my advice.