Play "City of Ashes" in the third campaign. When you help defend the HQ, you will be cleared to the hospital. Once outside the building, save the doctor who is crying for help in front of the gates. The zombie will appear from the right. While exploring the hospital, you will enter a room where a summoner is lying down with skeletons acting as his doctors. On the left are human remains and the message "You can still save him" will be on the wall. Meet the doctor you saved earlier and take his bag. Return to the room with the summoner and interact with the human remains. A man will appear and "We can still fix him" will be earned. Note: After saving the man, a gold bar will appear on the table.