The rotated working plane can now be used for drawing an object, such as a staircase, for instance.

After setting an appropriate placing grid - use the Grid snap properties .

Base Object > Prism

Start with the design of a staircase using the command " Place new prism".

Draw object in the 3D view

Each mouse click on your working plane creates a new point. 

After you have defined the last point, terminate with Return or double click the last point. 

To exit the edit mode, press ESC .

Note:  during the "D raw cube with the mouse" command, you can undo wrong entries with Backspace  

Enter your input with Return or double-click the last point.