If you have ever had to export Revit to AutoCAD, it probably went extremely well.Simply use the Export tool under the application menu, pick your AutoCAD version, and the views required. Easy as cake.
That is until you have a phased Revit project. Then you will notice that walls that are dashed in Revit are continuous in AutoCAD making it very difficult to tell existing from demo from new.
Never fear, here's what to do. Under Export in the Application menu, scroll down to Options and pick the DWG Export Settings.
This will open a new dialog. Select the Add (Edit Modifiers...) button. Find Phase Status on the left in the new dialog. and use the double arrows (>>) to move it to the right column. If you like, add a separator like a dash to include in the layer name.
This will create sub layers for phases under each category that has phased objects.
Life is now good.