That's a nice one. I had a L6 inside the evil mage/rune beetle spawn on Isamu Jima - I think the two of us trying to do it died a dozen times before we got the chest dug, from getting ganked by a dozen mobs at a time, and the spawn was even worse (the max of 8, adding hiryu, yamandons, oni, ladies and yomotsu elders to the bunch)