As I'm getting more used to Icecrown I'll post new Healing Through. As of now I've killed the three first bosses a few times and I'm getting comfortable with healing them. As always I'm mostly raiding in 10-Man, so strats and tips will concentrate on 10-Man raids, though I'll give pointers about the change you can feel in 25-Man.
So for today Healing Through, let's discuss Lady Deathwhisper, the second boss of Icecrown Citadel. You can read all abilities description on the WowHead page, and detailed strategy on the Boss Killers guide.
Lady Deathwhisper's room: Trash Mobs.
There are 4 pulls in Deathwhisper room before you can play with her. You have to clean all of them or you can be sure of a wipe on the boss.
Kind of like Grand Widow Faerlina in Naxxramas you have two cultist packs, they can be pulled separately if you take them from the side, and if you silence/grapple the casters to avoid any aggro-link from the second cultist group. No special difficulty, just take care that the melee mobs can spike your tank hard from time to time.
Then you have the two giant Nerubar (spider like creatures) at the back of the room. Single pull, single tank & spank fights. They cast a curse on one raid member that will hurt everyone around him, stay away from each other, with an empty room it shouldn't be hard in 10-Man. In 25-Man you can alternate to the group together strategy, the one being cursed moving away from the group. That requires more reactivity, but ensure minimal damage to the raid.
Lady Deathwhisper fight has two very different phases. During the first one she will have a mana shield, preventing any damage to her, but any damage will reduce her mana bar. As long as she has mana she will remain stationary and invoque adds to defend her. Once you reduce her to zero mana she will activates phase 2.
Pro-tip: try to not switch her to phase2 if there are still adds in the room, wait for your raid to clean one add phase then move her to phase 2.
I will describe her abilities and what to watch for healing-wise in each phase section.
In a 10-Man raid you should go for 2 tanks (mandatory), 2 healers and 6 dps. Being able to keep-up with the adds spawning is the key of the fight and sufficient dps is necessary.
Moreover you'll need about half physical and half magical dpsers, like 3 melees and 3 casters (hunters can be one or the other as needed).
This is kind of a tricky fight considering raid composition and you can't pass it with an all casters raid or all melee raid.
Healing is very different in phase 1 and phase 2 of the encounter.
Phase 1 healing is all about fast heals and reactivity, there can be a lot of sudden damage spikes on a lot of different targets (especially the two healers). And the boss aoes can bring several characters down at the same time, everyone should be hp topped at all times.
Phase 2 healing is mostly only tank healing, with much stronger hits than phase 1.
As you can see the two phases require very different healing options, and two different builds would be necessary to perfectly fit to the fight. But after some experience, phase 2 healing isn't really very hard for one reason: phase 2 won't last for very long. If you can reach it with full mana (and you should be able to) then you'll be ok even with a fast heals / raid healing build.
My view is to go with a fast heals build for raid healing, a Holy Priest or Restoration Druid will be perfect for phase 1 (characters will be fairly dispatched in the room and a Shaman will probably not be able to use Chain Heal as well as with the first Icecrown boss).
As a paladin, a fast Flash of Light build is perfect for phase 1, and it consumes so little mana that you will easily start phase 2 with a full mana bar which will allow you to spam Holy Lights long enough for phase 2 to end.
Healing Phase 1
(extracts from wowhead)
During phase 1, Lady Deathwhisper will have a mana shield that will absorb all the damage done to her. She will attack the raid with Death and Decay and Shadow Bolts - none of which should be too dangerous. On 25-player difficulty she will also mind control a random raid member for a short amount of time - CC them and move on.
She will also summon adds regularly during phase 1. Adds will come in waves from both sides of the room - mix of Adherents and Fanatics. In the 10-player version of the raid, the waves will come from only side at a time, switching sides. In the 25-player one, adds will come from both left and right side - one add will come from the entrance of the room as well.
Fanatics (melee adds) should be kited (preferably by the tanks) and killed by spellcasters. Adherents (caster adds) should be dpsed by the melee dps of your raid. Watch out for adds casting Dark Martyrdom, it means they will come back to life Reanimated in a few seconds.
The boss attacks aren't very dangerous, her Shadow Bolts hit for 7-9K and her Death and Decay for 4,5K/s (as long as raiders aren't lame they won't take too much damage from that). D&D can be more dangerous in 25-Man because characters will be more packed, you should assign a Holy Priest and a Druid specifically for that.
The difficulty is the adds. Fanatics cleave (but there should be no melee on them!) and have several regeneration abilities, they also hit hard when transformed if they are not kited/cced correctly.
Pro-tip: Always have one healer assigned to each Fanatic tank (2 in 10-Man, 3 or 4 in 25-Man). For Paladins, having a Beacon of Light on one of them is a very good idea to anticipate any spike on him.
Adherents have strong shadowfrost attacks that can aoe when they get empowered by Lady Deathwhisper. That can result in strong damage spikes on the melee group dpsing them.
Pro-tip: Adherents also tend to focus together on one healer when they spawn, which can result in 2 (10-Man) to 4 bolts targeting the same character, be ready for fast instant healing when they spawn (a Discipline Priest shield should be used on all healers before a spawn in 25-Man).
Pro-tip: You should also watch for mind-controls of a healer/tank and for the adherents curse that puts a 15s CD on all abilities you use when afflicted by it (decursing healers is a top priority).
In the end the first phase is all about being fast and over-reactive. Your raid members can greatly help by reducing the amount of damage the raid takes with proper movement and cc of the numerous adds.
Healing Phase 2
(extracts from wowhead)
Phase 2 begins when Lady Deathwhisper's mana barrier has been drained. Try not to have any cultists alive when that happens. The boss will become active and a tank needs to pick her up quickly, as there is no threat reset. A second tank will need to be available to taunt the boss, since she will periodically debuff her current tank with a stacking threat generation reduction debuff. The two (three in 25-Man) tanks taunt off each other every 3 stacks.
Players should be mindful of the Vengeful Shades that will spawn through phase 2 and will randomly chase people - get away from them! These shades are untargetable and will die after a few seconds. Melee DPS might want to set up an interrupt rotation, since Deathwhisper's Frostbolt can cause significant damage (read nearly OS a not well geared tank). She will continue using Death and Decay (and Dominate Mind in 25-player).
Healing in phase 2 is much easier, you mostly only have to spam the tanks. All Frostbolts cast by Lady Deathwhisper should be interrupted and even if damage spiked can happen, there should be enough healers to keep the tanks up without too much of a problem.
Shades can result in significant damage, but if raid members kite them properly that shouldn't be too bad either.
The only danger is the Death and Decay, it will hurt tanks and melee several times during phase 2 and a lot of members will take damage this time. Obviously the tanks will move Deathwhisper out of them, but mages and shamans (distance interrupts) need to check-out for Frostbolts at this moment because melee interrupts won't be able to do their job. As for phase 1, assigning a Holy Priest and Resto Druid to heal D&D damage in 25-Man is the best option.
For Holy Paladin this part of the fight isn't hard, just spam Holy Lights, and if you still have the glyph you'll get D&D splash heal as well on the melee raid members.
This fight can be quite hectic, especially in 25-Man, but it's still the one I enjoy the most from the 4 first bosses of Icecrown Citadel.
Have fun with this crazy encounter, and see you for another Healing Through.