It is possible to 'solo' to the flameshield in a 'suicide run'. Get see invis and see stealth of some sort (the tinkered goggles work nicely) and zone in and out of DT until you get a good instance -- one where the eyes are out of the way of the run from the left side to the skull. Then sprint to the skull, die, but get your update. Totem of the Owl and Totem of the Butterfly also gives the ability to see invis and see stealth. You could also use Vision Totem of the Cat if level 70+ that gives both abilities in one item.