The LOTRO videos on this page show all of the major boss fights in the Garth Agarwen instance. It's a fun instance and Turbine added some nice gear that you can get from running the instance. It used to be a very long and somewhat difficult run, but now it's broken up into three smaller instances. In one you will face Ivar the Bloodhand, Grimbark is in another, and the big instance has the Red Maid, Naruhel.
Boss: Naruhel, The Red Maid This is the big boss of Garth Agarwen. She is actually pretty easy now that the instance has been reworked. Turbine has adopted a dps approach to boss fights. This falls into that category. Basically focus on the boss, burn her down as quickly as you can. She'll root your tank and do some knockbacks so try to stay with your back to the wall. If you're low on dps you'll know it because you'll have a hard time defeating her and will likely wipe.
Boss: Ivar the Bloodhand This fight used to be arguably the hardest boss in the whole game. Luckily they reworked it so it's a little more manageable. This is a 4 man instance. It's another dps burn type fight, but with lots going on. You must take Ivar down quickly without killing the banner wights for hard mode. He drains power, drains life from his allies, and summons adds. It's really pretty hard. Basically focus on the boss. Have the off tank try to get the ranged adds off of the healer. Burn him fast or you'll wipe!
Boss: Grimbark The big tree ;) It's now a 3 man instance so it's not too difficult. Again bring your dps. You have to kill the tree without killing the hives nearby for hard mode. The hives heal the tree so without enough dps the fight gets ugly.
Boss: Vatar This boss guards the entrance to the Red Maid. He's kind of a nuisance. Just focus on him. You'll almost kill him then he goes invulnerable. A bunch of crawlers spawn, so burn those quickly. He'll then full heal and attack again. This time he will summon crawlers constantly. The key is to kill him fast. If you don't then too many crawlers come and you'll wipe!
Boss: Edan and Esyld The two wight brothers are the first boss fight you'll encounter in the 6 man instance. You have to fight them to get through to the Red Maid's area. Pretty easy fight. Clear the area of the pathing mobs first. Then kill the left hand wight first, followed by the right. Nothing too special to note here.
Boss: Dunlang This is a new boss added after the instance rework. Doing it on hard mode gets you one of those barter tokens. It's kind of a strange fight. You can't kill Dunlang's helpers... and he's invulnerable for a bit. You end up having to wait about 30 seconds while the tank holds aggro on the adds. Then burn the boss when he's active.
Boss: Blogkritar This is a new boss that you must kill to gain access to Ivar's crypt. It's an easy fight. He heals himself once and summons adds periodically. Other than that tank and spank.
Hope you enjoyed the LOTRO videos for Garth Agarwen... See you over in the other instances!