Prime Rib Roast on the BGE is outstanding! I do a reverse sear first going raised indirect at 250* to IT of 115. Rest it, take out indirect stone and get BGE to 550*. Then sear all sides for about a minute a side. I sear on a cast iron grid on a spider. It is excellent rare/medium rare end to end. Slice and serve with horseradish sauce. Excellent!