Tie in a white parachute post upright at the 65% mark and split a Coq de Leon/brown tail at the bend, about one shank length.
Wrap or dub a slim purple body from the bend forward to the post. Why: the purple body is the whole trick, a color trout key on across many mayfly hatches.
Wind a grizzly hackle parachute-style around the base of the post, 4-5 turns, and secure.
Dub a purple/dark-gray thorax around the post base to fill and lock the hackle.
Whip finish behind the eye and cement the post base.