While every fight in the heroic version of ICC is tuned to require a full roster of players performing at their peak, there is still often plenty of room for mistakes. A typical 10- or 25-man roster will have a druid in the raid to provide a Rebirth if a player dies, but it's not so simple on the Saurfang fight. Mark of the Fallen Champion will be doing massive damage to various players, so much that it can easily exceed the damage done to the tanks over the course of the fight. This debuff is what is most likely to cause a wipe, and if you use a battle resurrection on a Marked player, they will die immediately upon being resurrected. That's in addition to the fact that once a Marked player has died, the boss will heal for 20% of his total life, which will likely have you running into his enrage timer.
Basically, due to the boss' increased life on heroic mode, it's not possible to defeat him before he uses a few Marks of the Fallen Champion. Once active, your job will be solely healing the affected players, as the incoming damage is so high that you will not have an opportunity to pause your healing at all. This becomes especially true when the boss is below 30% and is attacking 30% faster, as this means your Marked targets are taking 30% more damage as well. The Saurfang fight starts with a whimper and ends with a bang, and so preparing yourself for that inevitable phase of absolute healing chaos becomes your primary objective.
Preventing Blood Power gains
Holy paladins have a few available tools to use in order to counter Saurfang's Blood Power gain, which will in turn slow down his Mark of the Fallen Champion casting rate. You'll want to use these early, as delaying the application of the first Mark is much more important than delaying the following Marks, since his BP generation scales dramatically with each Mark he throws out. You can keep the fight moving pretty smoothly if you successfully negate several of his early BP gains to delay the initial Mark.
Our two core abilities for dealing with BP generation are our bubbles: Divine Shield and Hand of Protection. If you ever have the Boiling Blood debuff on yourself, use Divine Shield to clear it immediately. In addition, if any non-physical classes have Boiling Blood cast on them, immediately use Hand of Protection to remove Boiling Blood. This will prevent him from generating any BP from these abilities and is crucial to making this fight as easy as possible. Holy/prot paladins are especially suited for this via Guardian's Favor, which will allow us to use Hand of Protection at least twice during the encounter.
Encourage any other paladins in your group who have a spare GCD to also clear Boiling Blood from any casters in the group (or themselves), while remembering that mages can also use Ice Block to counter it as well. By delaying the first Mark, you are reducing the total amount of BP that Saurfang will gain by a large amount and buying your DPS the time they will need to kill the boss before the Marks become impossible to heal.
How to heal through Mark of the Fallen Champion
It hurts. It hurts a lot. Mark will be dealing massive damage to whoever is afflicted by it, and that's where holy paladins tend to specialize. For the first Mark, toss your Beacon of Light and Sacred Shield onto them and don't stop healing for the rest of the encounter. Even if everyone is at full life, you can't stop casting for a second, as the player will constantly be taking damage. Using your mana regeneration abilities proactively will become very important, so don't be afraid to Divine Plea when you're at 70% mana if it's during a light damage phase. Watch your Marked target closely: if he is afflicted by Mark and Boiling Blood at the same time, he can lose over 50% of his life in one hit from both. Swap to Holy Light any time that your target is taking excess damage to ensure his survival.
One mistake on healing will end this encounter. This is pressure of the highest kind: every single cast determines failure or victory. You cannot afford to underheal your targets, as to keep overhealing to a minimum, you will really be the only one healing your Marks. The average length of this fight on heroic difficulty is about 5 minutes, and so your goal should be to sustain near-constant Holy Lights from the moment the first Mark goes out to the moment that Saurfang falls. Focus on any sort of mana regeneration that you can, including things like intellect trinkets and calling for Innervates and Mana Tide Totems.
You'll be healing your first Mark through Beacon of Light, until your second Mark becomes active. On 10-man, this will be the second Mark, as you are likely the only holy paladin. On 25-man, this will depend on how many holy paladins are in your raid, though typically you'll be handling Marks 1 and 4, 2 and 5, or 3 and 6. Once your second Mark is about to become active, immediately refresh Beacon of Light, Sacred Shield and Judgements of the Pure. You'll want all of these to be at their maximum duration, as if you pause to recast them later, you will lose your target. If you are forced to recast either Beacon or Judgements of the Pure, use a Hand of Protection on one of your Marks or call for assistance from another healer.
Frenzy means Holy Light spam
Once Saurfang is nearing 30%, recast all of your buffs for the final time. You will typically be shooting to take Saurfang from 30% to 0% in the 90-second window of your glyphed Beacon of Light duration. While Frenzied, a single GCD used on something other than Holy Light onto your second Mark will end in death and a failure on the encounter. Literally, you will push no other button than Holy Light, unless it is to activate a trinket or possibly use a mana potion if absolutely necessary. Try to use Divine Plea before 30%, as you won't have the time or the healing to spare afterwards. Don't try using a Hammer of Justice to help out your Blood Beast killers -- you will lose a Marked target. Don't try to use Divine Sacrifice to help the raid take less damage -- you will lose a Marked target. Don't do anything besides spam Holy Light, unless you want the responsibility for failing the encounter to be squarely on your shoulders.
If you happen to lose Judgements of the Pure after Frenzy begins, you are probably better off not judging to recast it. You can't spare the GCD, and typically you will have enough haste on your gear to handle keeping both targets alive without JotP. Beacon, on the other hand, is required, since there is no way possible for you to heal both targets before one of them dies. Try to recast Beacon right at 31%, before Frenzy engages. If you absolutely must recast Beacon of Light during Frenzy, call for both of your two Marked targets to use damage reduction cooldowns like Ice Block or Icebound Fortitude, ask for backup healing if possible, and use Hand of Protection if it is available as well. You cannot afford to miss a single heal to either target once Frenzy has started. It may seem like you could make some huge difference with just one simple non-healing cast, but realize that if you fail to have that Holy Light arrive on time, the entire raid will wipe and it will be only your fault. You must let go of Grid and focus on your simple task: keep two targets alive in the face of massive damage.
If you're doing your job well, then you have delivered the encounter into your raidmates' pocket. Without a holy paladin to handle keeping two Marks alive, the fight becomes nearly impossible in difficulty. We are perfectly designed to handle the predictably high incoming damage on the same two targets, which makes us ideal for healing through this encounter. If both of our Marks survive, then we have done everything in our power to make the raid succeed. Tank healing, raid healing and all aspects of DPS must fall to the rest of the raid, as we have a date with Mark of the Fallen Champion that we simply cannot cancel.
The Light and How to Swing It (Holy Edition) is dedicated to helping holy paladins become the powerful healers that we're destined to be. If you're new to the paladin's healing ways, you can learn the ropes with our Holy 101 article. We also have information on how to keep a tank alive, how to heal a raid when necessary and how to beat the GCD. Tanking is a job, DPS is a craft -- but healing is truly an art.