The information below has been verified with in-game data and the information on this page is correct, even if it looks stupid or makes no sense.Fact: zone name is "Kralet Penumbra: The Hive Mind [Raid]"
You have to be mentored down (grey mobs wont drop the chests) to kill two adds that drop two torches to open further bosses up after kill the 4 linked named boss (4th boss). Click one of the big braziers at end of room and one of the multiple braziers with the purple flames by the door to unlock the door. Each side unlocks each door. The end bosses room requires you to have the full crafted psionist helm to open the door. You can do this all solo.