Soloed today as an 85 paladin, max shielding & avoidance, about 4450 AC, with a Tier 3 Merc. She has a truckload of HP - at least 1.5 million. Fight took about 45 minutes. Dropped the fabled shield.
She hits a defensive tank (with 12% shielding) for high 2k's Casts AE Disjunction of Flame which has a mana drain component (is same AE as Arch Mage in PoFire) and Dark Inferno
MUCH harder than the King. Couldn't keep our healers cured.
This effect is most likely an agro list effect. So as long as you are within range of the ae it will hit you no matter where you are if you are on her agro list. This was Sony's answer to the "hide behind a wall to avoid the ae" trick. As far as I know all new mobs from OoW on are like this with their ae's.