16th Hall Guide
This is another instance where I have only done hard mode runs, so I do not have info on quest mode yet.
Hard Mode
The 16th hall is full of Globsnaga Orcs (the fungus infested kind), and gredbyg. It's a good place to get your deeds finished, and hard mode for this instance is fairly easy (compared to runs like Fil Gashan).
This instance works best if you have 2-3 hunters all with Rain of Thorns traited. Combat Traps is another very good trait to have here. A Lore-master with Proof Against All Ills traited is very helpful also, as all of the bosses do disease (this trait allows the skill Tend the Sick to work on your entire party).
Once inside the instance, you'll go straight for a good distance. There will be globsnaga to kill, sometimes in large numbers (hence why Rain of Thorns is very helpful, or having a LM use Herb-lore is great too). The first boss you will come to is Tramug.
Tramug has 2 minions, which are fairly easy to kill. This is the only instance I have been in where the hunters were told to be in Strength Stance; it helps a lot with this boss in particular. Use Quick Shot on him as often as possible to slow down his movements; he will cough and cause an AOE disease that does a pretty ugly DoT.
After Tramug is dead, you will need to head out of the right side door way (from where you came in). In this part, you need to stay away from any Bloated Globsnaga; if you get too close, they will explode and 4-5 crawlers will appear and attack you. You will eventually come to a staircase that leads down, and there is a fairly big room at the bottom. Set traps and Rain of Thorns or root one group of Globsnaga at a time. Once the first 2 groups are finished, some normal mob Globsnaga will appear randomly, kill these as fast as you can (they die quickly) or else they will explode into crawlers. Take the passage straight across from the stairs; this will lead you to a crossroads.
At the crossroads, you will need to kill the rooms both to the left and the right. There are wheels inside these rooms that one member of your group needs to turn. When both wheels have been turned, the door going straight at the crossroads will open into the second boss' room.
Boss #2 is Dhûrz. He also does a lot of AOE disease attacks, with a very bad DoT. Have pots, or a LM with group-wide Tend the Sick available. Have the tank and melee characters go to the right side of the room once inside, near the opposite (closed) doorway. Have your hunters on the opposite side of the room. Hunters need to be in Endurance Stance for this fight. When the tank aggros the boss, let them hit him several times before attacking. Hunters need to do auto-attacks only until the boss is about 10% down on health. Then unload on damage. It is VERY important to keep this boss' aggro on the melee group, as it is very difficult to regain aggro if others pull him away (hunters). The Hunters also have the secondary job of watching for Globsnaga adds; kill them ASAP, as they will explode into crawlers if you don't.
Once this boss is dead, the doorway on the right side of the room will open. This will lead into an area with several ledges you have to jump off of. Kill any elite Gredbyg you come across, until you have gone down into the green pool area. Here there are gredbyg Queens (elite) who summon multiple helpers at a time. Hunters should use rain of arrows as often as possible, champs aoe as often as possible. After killing all of the Queens, head down the next downward ramp.
The group I was with for this was using an exploit, so I have very little info on the last boss. He is called The Lost One (there is a quest from the 21st hall to kill him that gives a ton of legendary item xp). The group stood in the doorway to the boss room, and had the guardian use his bow to pull the boss toward him. The door then closed on top of the group, and the boss could not hit anyone. I don't know what the boss will do when Turbine has eliminated the exploit, but there is a pretty ugly debuff you get (even after the boss is dead) just from standing in the room.
EDIT: One thing I forgot to mention about the Lost One is that you cannot kill more than 3 of his minions while he is still alive, or it will break hard mode. This means NO AoE's, and NO reflect gear equipped. Once the Lost One is dead, the minions can be killed (because the treasure chests will have already spawned).
The Lost One drops the radiance set shoulder guards token (and also the housing decoration Fungal Mushroom).
Source: http://www.lotroalliance.com/viewtopic.php?f=32&t=797