After your encounters in the Arachnid quarter, you jump into the rabbit hole and are sent to the Plague Quarter!

Noth the Plaguebringer is more than a touch annoying. He has Curses, Magic Effects, and endless waves of skeletons. But really, it's a simple matter of learning the fight and being prepared, and mana- able, to heal when needed. This fight can get long. Ours was about 11 minutes. Of course, we had many fresh 80's, but, for now. 11 minutes. DK MT, with warrior OT for the skeletons, DPSing otherwise. If your group is as fresh as ours was, use your shadowfiend early, so you'll have it again later. The curses and magic effects need to be dispelled ASAP, the curses being the actual worry, Cripple is just annoying and may prevent your tank from grabbing Noth when he aggro wipes, so, dispell when you can.
While actually fighting Noth, it's pretty tank and spank. The tank doesn't take too much damage, and the only worry is the dispells.
When he teleports up to the balcony and calls down a bunch of skeletons, kill them as fast as you can. At first, there will be alot of raid damage because the skeletons attack random things. Though, they always spawn from the same side, so, myself and the druid just stayed on the opposite end at max range.
Keep everyone topped up, use a mana pot, and shadowfiend wisely and it's done!

Heigan the Unclean is about coordination. Really, it's kind of a pitiful fight. Keep up Abolish Disease, run away from the Eruptions, rinse and repeat. There is very little damage done to the tank during this. The only concern is people getting caught by the waves, which do around 7k per tick. We used smoke bombs to mark safe places, and stayed grouped up, far enough away from the Boss' platform to avoid the Spell Disruption (About 20 yds.) Run around, toss some DoTs, and Frogger doesn't die today.

Loatheb seems to be annoying, and horrid if you just read up on the fight. But, really, he's kinda easy. You have 3 seconds every 20 seconds to heal. So, for 17 seconds you can chill out, toss some DoTs, smite every now and then if you so please. Since we had the parties split into two groups for the spores, I never really left the general area of my group. Prayer of Healing is wonderful here. At about 1 1/2 seconds left of the debuff, I started casting PoH. It lands almost right after the debuff wears off, leaving plenty of time to throw out a flash heal, or two if you get the Holy Concentration proc. My party stayed healed the entire time. The druid's party was just as fine because he threw HoTs preemptively and let them tick. Shadow Protection may help with the DoTs, but not a whole lot. Still good to keep up, though. If your DPS is low, the raid starts to take too much damage, and will die to Loathebs DoTs before you are able to heal. So, get the free crit from the spores, and stay on your toes.

That concludes the Plague Quarter. Next, is the Military, or, Death Knight Quarter. =]