Protector's Realm
Once you defeat the 4 nameds your final task will be The Protector. The Protector is required for some of the epic weapon updates if people are starting to complete their mythicals. From the chest off the 4 nameds you will loot a rod which is required to destroy the totems/pillars in the main room the Protector starts in. One strategy to kill the protector is to drag him into the hallway where the 4 nameds were and position him in a little nook. Have your raiders stand on the opposit side of that nook the MT is at and begin the fight.
The protector at the start of the fight will unleash a nasty AoE which does varying amounts of damage based upon the distance from him. Each AoE comes about 25-35 seconds appart so you will have to have someone time it appropriately. When the AoE goes off have everyone start throwing on their debuffs to keep the creature from pounding away on your MT. After The Protector hits 45% health have everyone slow down their dps and be prepared to reapply their debuffs at 42% health. At 40% health you'll need to have someone shout to stop all damage to the protector.
At 40% health the protector will apply a reflective shield ability which will cause all damage to be directed at who he is targeting. This can instantly wipe the MT if a wizard uses their Ice Nova or an assassin uses their Decapitate ability. It is at 40% that you should receive a message saying the Protector is being shielded by the columns and it is here that you will have someone run in with the rod to destroy/disable the columns. For this fight is crucial to have atleast 2 rods and better to have 3-4 to make the columns go down faster. The columns can take as little as 2 hits and up to 6-7 hits before they crumble and the Protector is made vulnerable.
With the columns destroyed you will need to have everyone wait if The Protector's AoE hasn't gone off within the last 10-15 seconds. Once it goes off have everyone rush in reapplying debuffs and burning him down as quickly as possible. Every death heals this creature by 2%, however some good news is if he goes over 40% HP you do not have to destroy the columns again just keep burning him down. Eventually the Protector will die and you will find your master chest. For those getting their Mythical updates YOU MUST use the item in question within that zone to empower your weapon unless stated otherwise in the quest. This applies to wardens who receive the power source/tool from The Protector because the item is a no-trade and no-zone item. If you zone out you will loose it and will have to submit a ticket to get it back if you can.
Now that the Protector is defeated you can start venturing into The Temple of Kor'shaa and Venril Sathir's room/chamber.