Killed him with modestly geared lvl 85 Shaman (1330 AAs), Tier 5 Merc Warrior, and pet. You have to kill all the giants in the surrounding area first before the Fabled will become targetable. Some are hiding in among rocks out in front of the big stone walls. Requires some searching. Kill all the creatures roaming near the Fabled tent too because they will add during the Fabled fight.
I pre-buffed the Merc with Wild Growth, Talisman of Lynx, and Halcyon Whisper just prior to attacking. Debuff Fabled, Heal Merc, DoT Fabled, Epic 2.0 click, Talisman of Lynx Refresh, Heal, and so on. Not a difficult fight.