a tip (or little exploit if you wish):
in sunken crypts when digging don't dig everything. lean a bit to the side. this will prevent mobs from reaching you and you can shoot them from a safe distance.
i usually go into the crypt in troll4 (which is equal to bronze 3 armor) and have no trouble surviving. as long as i don't forget my food. but try to upgrade your shield\armor asap. it'll make your life much easier.