You will be facing Burun Ruuks and Burun Guruks in both dungeons and with the boss. All the monsters are commonly weak to frost and additionally a Critical Strike weapon will be needed for the boss fight.
Walk Through
King 4 Keerik Part 1
Using an Obsidian Rim portal (Aerlinthe, Caul) will portal you close to the Watcher of the Dead at 51.4S, 67.9W for this King.
You are portaled into the first dungeon after speaking to the Watcher of the Dead.
After completing the puzzle in the previous section, going through the Portal Gateway will progress you into part 3, the second dungeon.
From the drop, head East and hug the left wall all the way to the end (make sure to head down in the grated area), there are no misdirections other than that, and no levers.
At the end, you'll find a hallway on the east wall, which leads to a Portal Gateway. The device leads to Keerik, the boss.
Keerik's Lair after his defeat (notice the hides on the floor)
Lore & Dialog
Watcher of the Dead tells you, "My purpose is plain, I watch the dead that reside within the halls of this temple. I have stood this vigil since my sacrifice over thirty thousand years ago, when the world cooled and the darkness made war upon all. The weight of time has long crushed my bones to dust and left with me with this incorporeal form. Yet, I serve my purpose with the same vigor that I did in life."
Watcher of the Dead tells you, "I will not find rest until the threat from beyond is quashed. They will spread like a plague across this world if they are not shattered. Great waves of magic shall crash against their flesh and be pulled into their bodies. Their strength will grow until they can no longer be touched and then all shall be lost beneath the weight of their power."
Watcher of the Dead tells you, "A great failure for our sisterhood. They grew where our chosen fell. Now they come to shattered the coil of this world as we shattered the coil of theirs. You must defeat the behemoth within these halls else its power grow until it is unchecked by any force that remains on this world."