When designing buildings, we all know that we often get walls that are non-orthogonal and at various angles to the sheet. With those walls, we often want to get an elevation that is parallel to a particular wall. It is actually easy to do.
There are a couple of good options to make the elevation parallel to the wall.
Option 1 – When the Tag is Placed
When you place an elevation tag, move the cursor near the desired wall and you will see the elevation marker rotate to be perpendicular with the wall so that you get a scope box that is parallel.
You can go ahead and place the marker, and then move the marker to a new location that is further from the wall if desired.
Option 2 – When an Existing Elevation is Modified
When an elevation marker and view already exist, it can be rotated to match the wall’s angle.
With nothing selected, window the entire elevation marker tag to select it. (Don’t worry about the scope box.)
Go to the Modify panel and select the Rotate command. The little rotate icon will appear at the center of the elevation marker. Pick on that little rotate icon and move it to a point on the desired wall. You can now specify the rotation angle to rotate the elevation marker, or use the rotation line to specify the old angle and the new angle. Your selected elevation marker and associated scope box should now be rotated to match the wall.
You can move the elevation marker to the desired location for the marker.
The following image shows the elevation tag what would be selected for rotation and the new location for the rotate icon (center point for the rotation) and elevation rotation line. The final desired elevation marker rotation is also shown.
Applying Technology to Architecture 
Thank you for that fine explanation. Reading it reminded me of continuing the Revit training.