The Melting Pot is characterized by lava flows and fire-based enemies. You'll encounter Pythons, snake-like creatures that spit fireballs, and Incinerators, stationary turrets that shoot streams of flame. Fire resistance tonics (if available) can be helpful here. Prioritize taking out Incinerators from a distance.
The environment itself is a hazard, with areas of lava that deal damage if you step on them. Use your dodge roll to navigate these sections. Consider equipping weapons with good range or area-of-effect capabilities. The Mortar, if you've found it, can be very effective against groups of Pythons and Incinerators.