This post addresses both the 10-Man and 25-Man version of the encounter. The heroic version is not available yet (and won't for a few more months), I will update this post later for that.
Be happy fellow Holy Paladins, this is a fight for you, Beacon of Light will shine as never during this fight.
The path to the boss: trash mobs.
Some will say the trash up to Marrowgar are harder than the boss himself. Though this could be slightly too much to say, the packs are relatively interesting and some sort of control should be used before you aoe everything to death. More precisely the undead spider creatures should be cced by priests and killed separately after the other parts of the packs are done.
Pro-tip: the spiders on the sides of the first room can be soloed by using a Death Knight Death Grip ability
Now ... there is a "fun" surprise with these packs, the 4 Giant Bonelords in the walls of the 2 rooms before Marrowgar can activate and aggro you somehow randomly. I've seen only 3 activating, sometimes the 4 of them, sometimes during the first pack, sometimes not before the last one. It seems to be completely random, but to always occur when you're already fighting. A big emote will warn you a few seconds before one activates, and you'll have to deal with it quickly, as it's damage and aoe silence can be devastating.
If you're lucky you will only have one Bonelord then the periodic aoe, that silence you if you were casting, can be easily avoided and your healers won't have problem keeping the tank up. If you have multiple Bonelords, you will have 3 tanks to heal (the 2 Bonelords tanks and the tank dealing with the pack you were fighting) and 2 aoe silence to consider. On my about 10 runs through these trashs, both in 10 and 25-Man (I've done some reputation grinding runs :p), we've only survived 2 times to a double Bonelord and never to a wonderful 3 Bonelord bash.
To sum-up, cc the spiders and always have a spare tank ready to grab the random Bonelord.
Pro-tip: Most of the time, if more than one Bonelord activate while you're still fighting mobs, try to finish your pack quickly if you can and run for the exit, unless you have very good tanks and healers more than one Bonelord while already fighting a pack means raid wipe. Once they have reset, they can be pulled separately while they patrol.
Boss Description, Abilities and Raid composition.
First of all I invite you to read the boss description on WowHead, and WowWiki. And then you can go to the strategy guide on BossKillers, and the video on Tankspot - Project Marmot. Always basic reference for raid bosses. All of that will give you a good idea of the fight if you've not already experienced it.
The 3 mains abilities from Lord Marrowgar are: Saber Lash, Coldflame and Bonespike Graveyard. You can add to them his Bone Storm which is a sort of alternate phase of the fight.
He will use the first 3 during the tanking phase, but only Coldflame when he whirlwinds during his Bone Storm.
You will need 2 tanks in 10-Man and 3 tanks in 25-Man, just to share the amount of damage done by the Saber Lash.
Pro-tip: Lord Marrowgar's damage has been reduced in 10-Man and the life of the tanks isn't as in jeopardy as before, especially after a Bone Storm, but they still should be very reactive in the use of survival cds when needed.
The fight uses 3 healers in 10-Man and around 6 in 25-Man, more healers in 25-Man makes survival easier but the amount of dps is key as quick dps anywhere in the room is needed because of the Bonespikes.
The only tricky part of the fight is the end of the Bone Storm. When Marrowgar finishes it, he resets his threat table, and he is untauntable in 25-Man. Your tanks need to be quick at grabbing him and move him back near his original position. During this time, any aggro reducing ability is very helpful for healers (Fade obviously for priests, but using a bubble at that time as a paladin is a good choice to allow you to spam heal right from the start of the phase).
Pro-tip: Keep in mind that as soon as he stops his Bone Storm, he will starts his Saber Lash again .Tanks should be quick to gather, and use survival cds is needed. All other raid members should stay more than 10 meters away from the tanks to ensure none eats a Saber Lash whiled he's moved.
Focus on Healing 10-Man.
Pro-tip: in 10-Man the number of raiders is limited, you need to pay attention to the fact that at least 3 raiders should be out of the proximity of Marrowgar and in range of Coldflames, if you have fewer Coldflame targets he will use Coldflames on your tanks.
Most of the damage of the fight comes from the Saber Lashes. But there will be high short duration damage on the victims of Bone Spikes and random medium damage on the whole raid during the Bone Storm phase.
Two healers should be dedicated to the 2 tanks, usually the Main Tank will be a shield using tank to reduce the damage as much as possible as he will be hit more often. If you have a Holy Paladin in your raid (very much advised for this raid) he can heal one tank and beacon the second one, allowing the second tank healer to help with Bone Spikes and people being lousy at dodging the Coldflames.
The third healer will be healing the raid and the victims of Bone Spikes. He should react if ever needed to heal the tanks if one of the tank healers is in a Bone Spike.
Holy Paladin point of view:
I've been using a Flash of Light build during all ToC, this build is not enough for Icecrown, at least not enough for dual tank healing on Marrowgar. I'd advise you a pure Holy Light build for this boss, especially as the Aura Mastery and Divine Guardian talents can really help your raid if used at the right times.
As a Holy Paladin, healing while moving isn't your best asset. If you're assigned to tank healing, you will have to use Holy Light, which is a longer cast and will make you very bad at avoiding Coldflames. If you get close enough to Marrowgar, you will be inside the "Coldflame safe zone" where the tanks and all the melee dps should be. As long as at least 3 members of your raid are out of this zone to provide Coldflame targets to Marrowgar, this is the safest spot for you to be healing from.
In 10-Man you'll be a tank heal for sure. Ask for another healer to help you if one tank goes low, or much more importantly if you get taken into a Bone Spike. You should be able to do most of both tanks healing by yourself alternating between Holy Lights and Flash of Lights.
Pro-tip: Remember to judge Marrowgar regularly for your Judgements of the Pure, and keep your Light's Grace up too.
Take care to the tanks after a Bone Storm, remember to refresh your Beacon of Light, use your Devotion or Frost Resistance aura (depending if you have a Paladin tank or not) and you should be set for Lord Marrowgar. There isn't much else to say about the fight :)
Focus on Healing 25-Man.
The fight is not very different than it is in 10-Man. The main difference is the amount of damage, that makes every ability from Lord Marrowgar much more deadly. Notably, the Saber Lash will hit for 300% damage instead of 200%, and the Bone Spikes will kill someone in a matter of seconds if not healer.
3 Healers should be dedicated to the tanks, this is mandatory as one can very probably get Bone Spiked several times during the fight, preventing his healing for a few seconds. The 3 other raid healers should be dispatched in the room and on Bone Spikes heal duty with the random slow people on Coldflames.
Holy Paladin point of view:
You will be affected to tank healing most probably using your Beacon of Light on the main tank and healing one of the Saber Lash tanks with mostly Holy Lights. The amount of damage is superior and you will have to nearly spam Holy Lights for most of the tanking phases, especially when one of the other tank healers is in a Bone Spiked.
The difficulty then becomes mana regen. Divine Plea will be necessary, unless you have external mana regen (Inervation or very effective Replenishment with an insane amount of intellect).
Pro-tip: The ideal time to use Divine Plea is during Bone Storm, but be sure to survive. Pop an Aura Mastery to reduce the damage on the raid and about 15 seconds before the end of the whirlwind use Divine Plea. Then if up pop a Divine Shield and a Divine Guardian, trying to be sure that Divine Shield will be up for the first 5 seconds after the end of the Bone Storm, so you can bomb heal the tank without risk of pulling aggro.
Grats on your downs, and have fun with this fight, very frustrating until most of the raid is reactive enough, easy and crazy fun afterwards :P
As always, I hope this article was helpful, and I'll see you again in the next Healing Through.
Edit January 27th
We changed somehow our strategy on Marrowgar concerning the raid positioning. I guess it's probably a better strategy for more casual (read less reactive) raids that have issues with the switch on the Bonespikes.
Now we do everyone into the Coldflame safe zone, which means everyone is close to Marrowgar, slightly inside his hit box.
This has several advantages:
- nobody can get both into a Bonespike and a Coldflame, which avoid strong damage on anyone that could die before being freed from the spike;
- nobody has to dodge Coldflames, that helps all classes with casting times, both healing and dps;
- everyone is close together so switching dps on Bonespikes is faster as all dpsers can dps the spikes, melee dps included.
We experienced easier kills like that. So if you have issues with people dying on the spikes/flames or raid healing having difficulties with keeping everyone topped and then people dying during the whirlwind, try it too, it could be easier for your raid too.