From the beginning, go all the way to the end, make a few rooms to put production units, and use the place where many parties meet as a battle room. Run fast and open the door. If the crystal is above 60, just guard it. If you have less than 50 health, take a mouth medicine and you will basically not die. Powerful monsters can be tamed directly. Evacuate and let 3 people cover it, wait for the crystal to evacuate, and then follow up. It doesn't matter if two people die, they can be used as tools, as long as they are fully recruited