The Vai'kesh and the Aegis of Death - Act 2 Story Quest
The Vai'kesh and the Aegis of Death is the 5th Story Quest of Act 2 and begins when the Vai'kesh in the Vai'kesh Sanctuary become hostile to you at the end of The Royal Caravan. For the first part of this quest you're going to be chasing the Vai'kesh Prophet through the rest of the Vai'kesh Forest and then through most of Arinth's Ravine.
Shortly after the treasure room in the Vai'kesh Sanctuary while you're running up a flight of stairs you'll pass by a book on a bench, Vol 2. The Dark Wizards. If you plan to do the Lore of Aranna Side Quest later on during Act 3 I recommend you grab this book now otherwise you'll have to come back for it later.
While running through The Vai'kesh Forest and Arinth's Ravine just follow the main path. Your quest will keep updating with gold stars on your map as you progress through these areas, the Vai'kesh Prophet you're chasing lays out many ambushes for you which you'll activate along the way.
Side Quests In Area:
A Dark Ohm
A Family Heirloom (Part 2)
Eventually the Vai'kesh Prophet will stop running from you and give up in eastern Arinth's Ravine. Once he's defeated your quest will update one last time and tell you to claim the Aegis of Death further east of this location. Be prepared prior to entering the next set of large rooms as you'll be facing the Knotted Shambler boss in one of them.
Our next boss fight is going to be against the Knotted Shambler, much like all boss fights you'll want to switch to 'Mirror Mode'. For the first half of the fight your main target should be the Leaf Generators. Throughout the room where you fight the boss there will be multiple Leaf Generators that you can destroy - they will heal the boss as well as create little annoying enemies that swarm you. Until all of the Leaf Generators are destroyed any damage you do to the boss will be healed by them.
The Knotted Shambler is very slow and you can easily avoid most of its attacks for the first half of the fight, if he gets near you or pops up near you while you're fighting a Leaf Generator just switch to a different one across the room. Once you've defeated every Leaf Generator focus all of your attention on the Knotted Shambler and take him out. Chug Potions when you get low on health, assuming you're a few levels higher than he is you'll be able to eat all of his attacks. Your Casters/Rangers will take the most damage and may go down a few times during the fight but melee should be able to take all of his hits.
With the Knotted Shambler dead you'll be able to claim the Aegis of Death nearby after which our favorite friend the Azunite Scholar will appear and funnel us towards a back room with another portal. This quest will also complete and you'll start the next Story Quest, Princess Evangeline.