Fully upgraded troll armor.

Poison res potions are a MUST. This makes the swamps quite bearable, almost easy.

When you encounter spawners, be aware you will get overwhelmed so stick and move constantly and focus on one spawner at a time to destroy it.

Mark crypts on your map for future reference.

For food, of the top of my head boar and deer meat and queens jam. Once you get enough entrails, make sausages.