Massive pits with spikes in them.

Booby-trapped buildings and doors. Other traps that you can set off.

One building filled to bursting with alchemist fire and oil/tar/alcohol/whatever else that burns. Lure lots of kythons and undead here and nuke it as a last resort.

I think you'll have to fight tactically to survive, and even if you're clever as hell, you'll still probably go down.

Just remember that if things get hairy, you're more important than villagers. Even little crying babies.