Continue past the room and take a right at the next split.
Note: From here the dungeon becomes rather symmetrical, continue heading North.
Work your way until you reach a locked Outer Locked Gate (600 Diff), where you'll find a shadow named Dealith. Kill him and loot the Outer Locked Gate Key.
Use the key to open the gate, and continue until you reach another locked gate. This time you must kill Faurset and loot the Middle Locked Gate Key from his corpse.
Again, use the key to open the gate and continue until you reach another locked gate. This time you must kill Liantor and loot the Inner Locked Gate Key from his corpse.
Now, work your way through a series of Mukkir until you reach a dead end room. Clear it out and wait just a moment for Targor, the boss, to spawn.
You give Riordin Nightbane Frozen Black Crystal.
Riordin Nightbane tells you, "Ahh, a frozen crystal shard. The mages in the Order have had some luck with figuring out what this was. It seems that this is a fragment of some sort of Totem, similar to the Ice Totems built by the Ruschk."
Riordin Nightbane tells you, "We haven't been able to reconstruct the totem yet, as the pieces are small and badly damaged, but we are hoping to collect enough pieces to reconstruct at least one complete totem."
Riordin Nightbane tells you, "It is our hope to use this totem to learn more about the Mukkir, and possibly make a weapon against them."
Riordin Nightbane tells you, "It was a great risk and noble act that you undertook in acquiring this crystal and bringing it here. Sarkin has given me these medallions to award to those whom have aided us in this."
You've earned 29,175,981 experience.
Riordin Nightbane gives you Necklace of the Golden Flame.