Once your party gets around 70, some mobs have such a hard time spotting you, they break off combat. Since the game recycles mobs every day, and respawns only when you are not in LOS, they stay gone. The crabs on the beach are not a very good choice. The little garden in Upper Monastery, behind the Phooney statue is a good place to go now--you can close the door once you're in there. Just get a good way of putting them to sleep--a Bard, some Fairy Dust, or a Sleep caster with enough points to do it at PL3 consistantly. Then you can Sleep them all, and Combat will end in a couple rounds, and you can close the door. You can even reload your entry into UM until there's a bunch of them in there, and the practise will go quite fast.Not quite as good, but close, is if you run into a large number of Seekers in Lower Monastery, and drag them to the Ramp Room. They tend to stick in the fight if there's enough of them, and it's bright enough in there--and big enough that if you get in the right place they can spread out and all aim at you. (the most i've gotten for this was 14--one group of 6 and one of 8)