Upon entering Prosper Bluff, Rucks will explain the nature of Secret Skills. You'll quickly come across your first Secret Skill: Bellow. This skill unleashes a powerful shout that damages and knocks back nearby enemies. Equip it at the Distillery if you haven't already, and practice using it (F key) on the incoming waves of enemies.
New enemies here include the Squirts with Shields, which require you to either break their shield with a strong attack or flank them. Bellow is excellent for breaking shields or creating space. You'll also encounter Gasfellas, enemies that explode into a toxic cloud upon death. Kill them from a distance or quickly move away after defeating them to avoid the poison.