In case anyone else was wondering I have been experimenting with
[Restorative Amber] macroed with Vanish. It works a treat in regular encounters when you are in trouble and want to vanish and heal while immune but doesn't (unfortunately) work to avoid mechanics like Attenuation in either the normal or heroic versions of that fight. A shame as this would have been nice in the final phases of that fight where it all gets a bit hectic. Nor does it prevent falling damage.