I think that for big monsters and dungeons, you shouldn\'t be able to win without a good party that have a good training.
Imagine
The rogue:\"ok i\'ll go see what await us\"
2 min later......
The rogue:\"ok. There are 2 big skelettons and a ghoul, and they are near a monster spawning point. We should fight them here, after made them follow someone.\"
Healer:\"ok i can blind undeads with my new spell\"
Fighter:\"ok i enter first and make them follow me here, you blind them, and everybody can hit them then\"
mage:\"dont forget ghouls paralyze at touch....\"
fighter:\"ow...that sucks\"
mage:\"i can put a anti paralyze barrier around me, so i think i\'ll go as a bait, but the rogue should shoot some arrows to slow them, as i don\'t move quickly and that their hit will do me big damages\"
healer:\"i\'ll follow you, and heal you if needed\"
rogue:\"don\'t forget to only blind them when they\'re here. Blinded they won\'t follow anybody\"
everybody:\"ok let\'s do this\"
And the party win. If they had only gone through, without planing, most of them should have been paralyzed by the ghoul and killed then by the skeletons, and perhaps other monsters that would have spawned, as the group is near a creature spawn point.