Skumfil Guide

There are 3 ways to run the Skumfil instance. I found the story within the instance to be pretty interesting. If you run the "left side", you fight kergrim and deep-claws for the most part, then the last boss is a gredbyg queen; the queen has a dead kergrim at her feet. If you run the "right side", you fight mostly gredbyg, and the last boss is a kergrim, with the gredbyg queen (from the other side) at its feet. Basically, the instance is a war-zone between the bugs and the corpse-eaters. Fun times.

Left Side (quest mode)

As you enter the instance, you'll take a left at the edge of the pit (hence why it's called left side). There will be several groups of creatures; one Kergrim summoner surrounded by several gredbyg. The summoners call cave claws to help them, unless they are interrupted (by champ's clobber, or similar skill) or unless they are mezzed (burg mez does work on these).

After you get past the first few groups like this, you'll come across the first boss - Bonetooth. Bonetooth is a fairly easy fight; he doesn't do anything noteworthy, but does have 2-3 cave claw helpers. After Bonetooth is dead, follow the hallway on the left just past where he was.

There are more summoners and bugs in the hallway, which winds around to an open room eventually. Inside the room is the next boss: Old Gnawer. Old Gnawer has 2 cave claw minions, Rockjaw and Shalebiter. Old Gnawer will put an eye icon over various people in the group; when the eye icon is over your head, you have been selected as "meat" for the cave claws, and they will attack you. The best way to get through this boss is to have the main tank go after Old Gnawer, and the rest of the group dps on one of the cave claws at a time. This fight usually goes pretty fast.

The minstrel level 58 class quest requires you to go into Skumfil's left side; the boss needed for this quest is Cracktooth. Cracktooth is summoned by an alter on the right-hand side of the room Old Gnawer is found in. Once this encounter is started, there will be several waves of elite cave claws to deal with before Cracktooth finally shows up. This quest works well if you have AoE classes (champs especially).

After Old Gnawer, etc. are finished, continue following the hallway around. It will lead you to the final boss of the left side instance, the gredbyg queen, Brumbereth. Brumbereth is not too difficult if the party makes sure their healer doesn't get too much aggro. This boss summons waves of little gredbyg, and also some larger gredbyg that do a VERY long mez on group members. This mez CANNOT be cured with the LM's stun removal skill. The only way to deal with these is to kill them quickly and interrupt them with clobber (or similar skills) as often as possible. Brumbereth does some poisons that can be pretty nasty if not taken care of; make sure your group has distilled poison pots. Anything below distilled will not work (for any status effects in this instance). Brumbereth does drop a very nice teal cloak that is good for melee classes sometimes.

Right Side (quest mode)

As you enter the instance, take a right on the edge of the pit. (Note: You cannot do both left and right side in the same run. You have to leave, disband, and reform in order to do both halves of this instance). On the right side, there are also groups of creatures, but these are spitter-type gredbyg surrounded by little gredbyg. AoE's work well for these. One thing to watch out for on this side is the blind crawlers. They are similar to the Crazed Globsnaga in the 16th hall instance; you need to kill the blind crawlers as fast as possible (they are normal mobs).

Just around the corner of the pit on the right side you will come to the first boss: Uammaethor. This boss goes down pretty quickly and doesn't really do anything interesting.

Follow the right edge of the room around to a hallway. There will be more bugs to kill inside, and will eventually lead to another large room. Inside this room are 3 bosses: Ulugon, Nestaduan, and Grog. These bosses run similar to the Old Gnawer on the left side, with the exception that Grog also summons little gredbyg to help out during the fight. Again, AoE's are very helpful here. It's best to kill Ulugon and Nestaduan one at a time while the tank stays on Grog. If you have a champ in the group, have them AoE like crazy.

On this side of the instance is a boss that is required for the champion's level 58 class quest: Longpincer. Longpincer is located up a ramp on the left side of the room where you fight Grog. When Longpincer is summoned, he comes alone, and he dies pretty quickly.

After killing Grog, there is a hallway on the right side of the room that you can follow. There are a few more bugs to kill on the way to the last boss on the right side of this instance: Grimreaver. Grimreaver can be a very tricky fight. Make sure your group has distilled disease pots and plenty of power pots. Grimreaver sometimes hits taking over 2500 power in one shot. The disease he does is AoE, and does a DoT for upwards of 600 a tic. A LM with Proof Against All Ills traited is very helpful here, but this boss can be done without a LM.

Grimreaver should be tanked (preferably by a guard, but a champ in glory stance can do it). He will summon cave claws to help him in waves. When the cave claws appear, everyone except the tank should focus on killing them as quickly as possible. Once ALL of the adds are killed, go back to the boss. He'll summon another wave, do the same thing. Kill all the adds before going back to the boss. If you do not do this and focus all damage on the boss, he will summon more cave claws than your group of 6 can handle, and the group will wipe. Grimreaver is much more difficult than Brumbereth from the left side.

If you kill both Brumbereth and Grimreaver, you can get the key that unlocks the door for hard mode. If you want to get the key, be sure to loot both Brumbereth and Grimreaver - they each have an item. One will start a quest, and the other will finish it. The quest turns in at the Shadowed Refuge, and gives 9k xp, as well as the key for hard mode.

Hard Mode

Hard Mode REQUIRES the key I mentioned above. When you go into the instance, you will drop down into the pit directly in front of you. There is a group of 3 spiders here that you'll need to kill, and to the left of the spiders is a door that can only be opened if you have the key.

Hard Mode is aptly named for this instance (if you do it without exploits, as it's intended). Once you are inside the door, you will need to watch the Globsnaga guards. They wander, and if aggroed they summon many many helpers. If you have more than 1 guard on you at a time, you can be fighting spiders for 5+ minutes before you finally kill them all.

The best way to do this fight is to watch the guards and wait for them to wander far enough away for you to move. Have the tank go in first; you will need to stay close to the right-hand wall, and pull the non-guard spiders into a little alcove not far from the door. Fight these off. Wait for guards to path away, then pull the next group while you are still in the first alcove. Kill these. Wait for guards, then run to the next alcove up the wall. Kill anything that follows you. Pull any groups that are nearby, and kill them one at a time. The next move you make will be to a red-colored hill against the wall. Have your party stand on this hill.

The tank now goes to aggro the boss (very big spider!) The tank will come back near to the hill, but NOT on it. If the spider starts to "dance", move out of the way! It drops an acid, and if you are standing in it for more than 3 seconds you are dead. This boss can wipe a group very, very quickly, and if it's from the acid, there is nothing you can do to prevent it. The best way to beat this boss is to have 1 or 2 champions spamming clobber for the duration of the fight. Clobber will interrupt the acid drops, but this also means the champs will not be available to AoE the adds much.

This boss will also run away twice during the fight, and bring back helpers. When she does this, you will need the group on the hill to take out the helpers while the tank stays on the boss. It is also very important to note that the helper will aggro your healer very easily; keep them off the healer at all costs. They interrupt heals very frequently, and there are usually enough of them that come that if they aggro onto the healer they (the healer) aren't going to be able to do anything.

This boss also poisons. Make sure your group has distilled poison pots. The hunter(s) need to be on dps, and not on curing poison for this boss.

If you do manage to survive through the fight (which is very possible), this boss drops the radiance gear token for pants/leggings.

Source: http://www.lotroalliance.com/viewtopic.php?f=32&t=801