Here is a good video showing the cascading lookup drop down field using New Responsive Design forms. It's connecting to a Sharepoint list as the data source.
However, this version of forms only allows for one condition. As the attached screenshot shows, there is currently a place for only one condition. There are instances where multiple conditions need to be applied. Would be nice if there were a "+" or "And" option there where you can add more conditions, much like you see on other multi-condition Nintex actions you see in workflow.
A possible scenario is also attached showing why more than one condition is needed for further filtering of cascading drop down fields.
Thank you very much for posting your feedback for our review. At this time, we will not be adding this request to the near-term backlog, as we are focused on other highly requested features. However, we reevaluate requests every quarter and will reach out if priorities change. Please keep the feedback coming as it is critical for our longer-term planning.
Thank you for your feedback, I will now open this for voting.