The pre-Noth trash is notable for the gargoyles and the slimes. The slimes are devastating on melee, so if the silly rogue manages to kill himself on the slimes, don't blame yourself. They really should be kited. As for the gargoyles, they should be focus fired one at a time so they will not have a chance to use Stoneskin and heal themselves. They do a stacking Acid Volley attack which can really wear down the healers if they are not dps-ed and eliminated properly. Don't forget to keep healing after the gargoyles are dead until the debuff wears off.
The pre-Heigan trash is what used to be a gauntlet run from Noth's room to Heigan's, but in Wrath is simply a tunnel full of maggot packs, bats, and the occasional fungal monster. AoE goes crazy here and there's nothing to really do as a healer except watch that the tank doesn't go down (and he probably won't).
The path between Heigan and Loatheb though, is still a gauntlet run. What my guild usually does is send the tanks in first. They drop any AoE threat abilities as they go (Death and Decay, Consecrate, etc) to pick up the maggot packs and the raid runs behind them. Ranged dps will use instant attacks to kill any eye stalks that threaten the party, but we do not stop and we do not otherwise dps or heal until we reach the doorway on the other side. Then we'll stand in the doorway and AoE down any maggot packs that followed us and heal the tanks. The maggot packs respawn quickly so it's important that the raid makes it over to the other side as a team.
Noth the Plaguebringer
Noth is not a tough boss by any means. He doesn't hit that hard and there's not a whole lot of raid damage as long as there is someone who can remove curses. This fight typically uses two tanks, though I think if someone overgears it by a lot, one tank would be feasible.
During Phase 1 Noth will hit the MT and the OT will be handling all the adds. He'll periodically curse three members of the raid with Curse of the Plaguebringer, which paladins can't cleanse, but can be removed by druids, mages, and resto shaman who have specced for it. If the curse is not removed after 10 seconds the affected party member(s) will explode, hitting everyone in 30 yards for 3700-4300 damage and another 1313 to 1687 Shadow damage every 2 seconds for 10 seconds.
On 10-mans it's not expected that the raid will have anyone to de-curse so this damage can be healed through if necessary. Aside from any curses, the only people taking damage during Phase 1 should be the tanks. It's possible that as a healer you may get an add on you if the OT is slow to pick it up, but they don't hit too hard.
In Phase 2 Noth teleports away and the raid will be focused on AoE-ing down the skeletons spawned during Phase 1. You'll still primarily be occupied with healing the tanks, but Phase 2 spawns new and different skeleton adds. The Plagued Champions will Mortal Strike (ewww) the tank and Shadow Shock the melee. The Plagued Guardians will Arcane Explosion everyone withing 30 yards of them.
The raid damage is not very high, and chances are a good resto shaman or a good resto druid will do a fine job healing through all of this while the holy paladin is left playing a futile game of whack-a-mole as I was. My healing on Noth was not all that, but that's okay. This is not a fight where we shine. Just spam FoLs where possible and make sure the tanks don't get hit too bad (and they probably won't).
I Beaconed the main tank, but after looking at the WWS our off-tank actually took more damage, so it's probably safe to Beacon either one of them.
Heigan the Unclean
The infamous dance boss doesn't hit very hard, but he does have a couple annoying things about him aside from the obvious dancing.
Phase 1 of Heigan involves the tank and the melee moving back and forth across the four "quadrants" of the room to avoid the slime that sprays up from the floor. Ranged dps and healers stand on Heigan's platform.
The first thing to be aware of is that there is a disease called Decrepit Fever that needs to be cleansed off anyone that gets within 20 yards of him. Generally this only affects melee, but sometimes it'll get ranged and healers if he uses it while transitioning from Phase 2 back to Phase 1. Having a shaman around with a Disease Cleansing Totem helps tremendously, but if you don't have one you'll have to cleanse the hard way.
The second thing to be aware of is Spell Disruption which increases the cast time of all spells by 300%. As a holy paladin you just can't have this on you! The ranged group shouldn't be hit with this unless the tank is running Heigan too close to the platform during Phase 1. If you get it, the tank needs to tank Heigan farther away.
Phase 2 is the fun part, and it's seriously a fun fight once you get the hang of it. At this point Heigan teleports back to his platform and because of the crazy dot he puts on anyone near him, the whole raid has to get off and "dance" across the four quadrants that previously only the melee had to go through, only now the sprays of slime come faster.
As a paladin we don't have much in the way of instant heals. Holy Shock is on a 6 second cooldown. If you can spare the mental bandwidth to do so, it's not a bad idea to heal someone with it, but no one should be taking damage during the dance. If they do, they're probably going to die through no fault of your own.
I've found that most people die their first time on Heigan, so there's no shame in doing so as a first timer. If you're confidant though and have enough haste going, I've found that I can just barely squeeze out a Flash of Light between sprays. Sometimes. It depends on how much I have to move and have moved. I don't think it's something that will make or break a raid, but if someone needs to be topped up to survive the next slime spray it could be handy.
Towards the end of the fight it was more likely I would be tossing a Hammer of Wrath in between slime sprays rather than try to pull off a FoL (assuming Holy Shock is on cooldown).
I was very proud of my Loatheb fight, because it's about as anti-healer as you can get.
The important thing to know about Loatheb as a healer is that he puts out a Necrotic Aura that for 17 seconds prevents any healing from working. This includes potions and bandages! Once the 17 seconds are over, there is a 3 second window during which the raid can be healed, after which the Necrotic Aura will be restored.
This means that healers have to maximize their healing for the brief period of time that they're allowed to cast (and the dps have to be fast before the Inevitable Doom casts become too frequent and overwhelm the raid).
Loatheb is considered a fight where Circle of Healing and Wild Growth from priests and druids really shine, but paladins can do respectably well.
This is the WWS for my first outing on Loatheb.
Mind, I was quite shocked when I saw this because I was quite certain that I'd be bringing up the rear with my single target heals, especially with a resto druid in the raid.
So what did I do right?
First, when the fight starts, make sure Beacon of Light is up on the tank. Sacred Shield him and the rest of the raid if you get a chance. This will reduce some of the damage they'll be taking. Loatheb will set up his Necrotic Aura soon.
Then, while the aura is up... dps him. You won't be doing anything else at this time and it's best to make sure Judgements of the Pure is up for the haste bonus. Using Holy Shock offensively will give you the chance to proc Infusion of Light, which could be a big help if you're caught by surprise when the aura wears off.
You should see a 3 second warning when the aura is about to wear off. If you have a mod like Deadly Boss Mods you'll even get an extremely handy timer counting down to tenths of a second. This is key, because to maximize healing you'll want to get off not just one, but two Holy Lights.
Start pre-casting Holy Light so that it'll go off the second the aura wears off. Then start casting a second one. The second one will cast pretty fast because you should have both Judgements of the Pure and Light's Grace up. Together with Beacon that's the equivalent of four HLs being cast in the narrow space of 3 seconds.
You won't be able to save an entire raid this way, but you'll be able to solidly heal three people and maybe get some splash heals on the melee with your Glyph of Holy Light. I would generally pick the people with the lowest health and then let the Beacon take care of the tank.
Healing 10-man Naxx Overview - Part 3 - Military Quarter
Healing 10-man Naxx Overview - Part 4 - Construct Quarter
Healing 10-man Naxx Overview - Part 5 - Sapphiron and Kel'Thuzad
Healing 10-man Naxx Overview - Part 1 - Arachnid Quarter