Leave the hut and ski down to the east side of Lac long where you can put your skins on. From here skin towards the moraine and ascend this to gain the Glacier de la Grande Casse. Choose the easiest angled terrain on the moraine, you may have to carry your skis if it has stripped of snow.
Follow the Glacier de la Grande Casse towards the Col where it starts to steepen. Further up it may be easier to transition to crampons and carry your skis. The col is narrow with towering rock walls either side and is very unique and wild place ! After transitioning the ski down starts with traversing along a glacial bench. Don’t forget to look up at the Grand Casse north face as you ski down but also be aware you are skiing parallel to any crevasses ! Chose your line and don’t drop too far down. You will turn to the north and leave the glacier here and if the timing is right there could be some excellent spring snow. Enjoy the excellent fall line skiing to the flattening near the Refuge de la Glière. Pop your skins on for a short distance before transitioning and skiing down the road to Le Laisonnay. If you're doing this tour earlier in the winter the road may be shut, in which case take the ski de fond tracks towards Champagny le Haut.
Finally, after five epic days, enjoy a well earned drink and some food in one of the restaurants at the road end.