The attendees will need to have a decent grasp on Object Oriented programming and need to have heard of Domain-Driven Design.
They'll walk away with more knowledge about their application state and a concept called Event Sourcing (ES). What is means to persist to the database without ES. When to use ES, but especially when not to use it. The concept is easy to understand, but the implementation details and possible rammifications of using it in the wrong places are pretty devastating. A good guide in the early phases of learning this concept is hugely important.
I'll give them the tools to get started, guidelines to follow and what to look for when they start implementing ES.