This one was already nearly finished, so I'll post it before I move. Have fun in ICC everyone.
Deathbringer Saurfang is the fourth boss of Icecrown Citadel and the end of the entrance part. It was considered as the second test of Icecrown, the first being the purely gear check of Marrowgar. Saurfang is a healing and dps check, if you can finish him, you should be able to try the inner halls.
For a guild at least partly in T10+ items and with the new buff Saurfang should not be a problem anymore. Your raid should still know what to expect, or you can be sure of a raid wipe.
Deathbringer Saurfang: Trash Mobs
This will be a short section, the reason being that there is not a single mob between the gunship battle and the fourth boss of Icecrown. The only opponent you'll have is waiting for npcs to finish their speech (especially if you're horde).
Saurfang has relatively few abilities, but they have all to be mastered by your raid to kill him.
The first mechanic is Blood Power, this will increase Saurfang damage through the fight. When his Blood Power is low, his damage will be light and healing the tanks will be easy, but it gets harder with his blood power increasing, at 100% Blood Power he hits twice as hard. You should understand that every damage taken by your raid during the encounter give Blood Power to Saurfang, hence one key of the encounter is to reduce damage and shorten the encounter as much as you can.
Pro-tip: All damage prevention abilities are extremely effective during that encounter, a discipline priest is nearly overpowered with his shields that can reduce Saurfang Blood Power influx by more than 50% in 10-Man. If you have any damage prevention ability, use it as much as you can.
The second main ability is Mark of the Fallen Champion. This ability is used each time Saurfang Blood Power reaches 100%, and resets it to 0. The target of the mark will take damage each time Saurfang hits the tank (around 4K each 2s). You have to understand that this additional damage will also give Blood Power to Saurfang, hence with each Mark he will gain more Blood Power, and will cast the next Mark faster. This ability is Saurfang "time limit" mechanism. It adds up to his enrage at 30% health which makes him hit faster, hence producing more Blood Power, especially if several Marks have already hit.
Pro-tip: Oh last thing, if anyone hit by a mark dies, never ever battle rez him, as the mark sticks through death.
Saurfang has two other abilities that will generate Blood Power for each character hit. The first is Boiling Blood and the second Blood Nova.
Blood Nova is only cast on members at range and hits the target and anyone in 12 meters. It is the reason why your raid ranged and healers should be all 12 meters apart (in 10-Man) or positioned in groups of 2 or 3 characters each 12 meters apart (in 25-Man).
Boiling Blood is a dot, you'll have to heal it nothing else to say.
Pro-tip: Boiling Blood will generate Blood Power with each tick, if you can shield the target that is a must, if you can Hand of Protection the target that will remove the dot, preventing 8 Blood Power for Saurfang, do it fast. What you should know is that Boiling Blood can be cast on the target of a Mark of the Fallen Champion. This is one of the main reasons for losing a Mark target and could be a good reason to keep your Hand of Protection.
Rune of Blood is the reason you need two tanks during the encounter. They should switch as soon as this debuff is cast on the current tank. Nothing else to say.
The last ability of Saurfang (did I say he had few abilities ... he does have some but most of them only impact healers) is Call Blood Beast. This calls for 2 beasts in 10-Man and 5 in 25-Man. These beasts need to be dpsed quickly and most of all they should *not hit anyone*. Anyone hit by a Blood Beast will give Blood Power to Saurfang. The best is to use all what you can to prevent them from reaching your dps, hunters Frost Traps are one of the best tools for that.
Pro-tip: All melee, the tanks included, should avoid any sort of aoe damage when the Blood Beasts pop. If they don't, the beasts will stay hitting them and Saurfang will gain a big amount of blood very quickly, which can cause a raid wipe a few minutes later when the marks are too numerous for the healers to endure.
If you want more details you can find very good info on Bosskillers or Tankspot.
Both in 10-Man and 25-Man you need 2 tanks. This encounter being a dps-race, you need to take as few healers as you can, usually 2 in 10-Man and 5 in 25-Man.
This will put a lot of pressure on your healers, and they will need a very good mana sustainability to finish the fight.
Pro-tip: Though spellpower is obviously important for healers, this will be more an endurance fight. If you have any source of mana replenishment in your raid you should save it for your healers in this fight if they need it, an oom healer during the last 30s of the fight will seal your fate.
The rest of the raid should be dpsers, both melee (they will be 100% of the fight on Saurfang and the main source of damage to him) and ranged (they will spend a large portion of the fight dealing with the blood beasts). Don't forget the ccers for the beasts that can be slowed, rooted ... anything but completely cced (no fear, mc or anything).
If you have a shaman, keep the Heroism/Bloodlust for the last 30% of Saurfang, you can call for it as soon as he enrages.
As I said, expect this fight to be very very mana consuming and put a lot of stress on your shoulders. Especially until all members of your raid master it. The more blunders there will be (blood beasts staying on the melee, tanks not switching fast enough ...) the more marks you will have to deal with at the end of the fight, and the harder it will be.
Remember you'll have to heal the tank and a few raid damage at all time (nova, dot, beasts). Each time a mark is cast, that will need at least half a healer attention to keep the target alive.
The last thing that I didn't say in the boss description is that for any death in the raid, Saurfang will regain 5% health ... this obviously means that you have to keep everyone alive as much as you can, Saurfang is not a boss you can finish at the very last moment with only 2 raid members alive.
In 10-Man you won't be able to endure more than 2 marks for every long, and most probably not more than 1 death.
In 25-Man if your healers are good you can manage up to 4 or 5 marks depending on your raid composition, and you can probably win with 2 deaths. More will probably lengthen the fight too much.
Whatever your class is, aim for fast "small" heals, as much damage prevention as you can, and the best sustainability you can get.
Use your mana cds as soon as you can get the full benefit of them, and if you can't use them during a strong healing phase, before the first mark is cast.
Paladin Healing tips
Holy Paladins are among the best healers for this fight, with Discipline Priests, but for very different reasons.
A Discipline Priest can greatly reduce the amount of Blood Power gained by Saurfang through the use of Shields.
A Holy Paladin can use his Beacon of Light to heal the target of a Mark of the Fallen Champion and continue to heal the raid. He can even heal both the first and second marks by himself.
Until the first mark is cast, the healing is light. But, as a paladin, you will have much more job as soon as a mark is cast. In a 10-Man raid you will most probably be the only Holy Paladin, and the two first marks will be your job. In a 25-Man raid Holy Paladins should share between them the first marks, 2 per paladin.
Once your first designed mark is cast you'll need to cast your Beacon on it (and remember to refresh it, use your focus frame or an add-on for that) and start cast continuous heals on the raid.
Pro-tip: You can never stop healing for much more than one gcd or your beacon target will die especially if it's a clothy (mark damage is physical and reduced by armor). Remember to recast your beacon/judgement when your Holy Shock is up in case you need the speed-up healing boost.
Once your second designed mark is cast you'll need to keep your Beacon on your first target and heal the second mark regularly, keeping both alive.
Pro-tip: As soon as your mark is cast you will not be able to stop healing, or use a Divine Plea because the healing reduction will be too strong. Try to use it before your assigned mark is cast (use Deadly Boss Mod to check Saurfang Blood Power), you should be full mana when you start healing a mark.
Remember to recast your Jugement of Light on Saurfang, both to increase your casting speed, and to heal your raid.
Keep in mind that your Hand of Protection removes the Boiling Blood dot, it is your choice to use it as soon as you can in the encounter, and have the opportunity to use it again later at the end of the fight. Or to keep it to protect someone being "double hit" by a mark and the dot (this can be very hard to keep up with healing wise).
Good luck and have fun, though very chaotic at first this is a quite fun encounter once your raid will master it.