Stay in melee range.
Stick with your normal tanking rotation.
Taunt when the other tank gets Rune of Blood.
Call for a taunt when you get Rune of Blood.
That's it. There's a crap-ton of stuff going on in this fight. But the vast majority of it is for your DPS to worry about. More specifically, the vast majority of it is for your ranged DPS to worry about. And to a smaller extent, your healers. You? You're not special. Not in this fight.
But that doesn't make for a very interesting guide, so let me see what I can do here without just rehashing something you might find on StratFu or BossKillers.
The reason you want to stay in melee range is because Saurfang will be randomly casting Blood Nova on people in your raid outside of melee range. It doesn't hit the person he casts it on, but it does hit everyone within 12 yards of them. If you're near the melee but not in melee range, you're going to smack them all with this, and that's no good.
At regular intervals, Saurfang will summon 2 Bloodbeasts, one to his right and one to his left. These will need to be aggroed and burned down by the ranged. One thing that is useful here is Bash. Every other summon (or every summon if you happen to be fully specced into Brutal Impact) you'll be able to take a moment to stun one of the adds. This will give your ranged a few extra seconds to deal with one before the other starts chasing them. You can also Growl at one of the adds that's far getting too close to the ranged to help with kiting. It's important no one starts actually getting hit by these things. (Just be careful with this...you don't want to have to wait for 8 seconds for your Growl to come off cooldown if the other tank gets Rune of Blood applied to him.)
There's also Boiling Blood getting tossed around, but there's nothing you can do about that whatsoever.
Now the reason it's important to not take damage in this fight from anything Saurfang does or anything his Bloodbeasts do is that every time damage occurs he gets a stack of Blood Power. You can see it in his unit frame where the enemy's Mana/Energy/Rage appears. Every stack he gets increases his size and damage by 1%. When he gets to 100 stacks, he dumps it all and casts Mark of the Fallen Champion on someone. That person will then be taking significant extra damage and it will exponentially increase the rate at which Saurfang gains Blood Power through the next 100 stacks.
At 30% health, he frenzies, so hooray for that.
A few notes here:
If you are a Bear that carries around more than one set of tanking gear, put on your Dodge set for this fight. Even when he's high on stacks of Blood Power, he doesn't hit exceptionally hard. And the more you can dodge, the fewer stacks he'll get.
I like to start this fight off in Cat form, letting the other tank hold him until the first Rune of Blood cast. I wait for the tank to get a little aggro and then pop Tiger's Fury and Berserk and go to town. It's a little extra damage right up front and it can help a lot later. As soon as Berserk wears off I shift into Bear, move in front of him, and get ready to taunt.
During this fight I replace Growl with this macro:
/tar DeathbringerThis way, if I'm helping burn down an add or throwing a battle res or anything, I can still taunt Saurfang immediately (sans shifting) when the other tank gets Rune of Blood.
A few more notes not specifically related to tanking:
Two reasonably geared/skilled healers can handle this fight if everyone else is doing their job right. Having a 6th dps really helps.
In our guild, we let the first person to get the Mark of the Fallen Champion die (unless it's one of the tanks). Yes, it sucks for that person and it does heal Saurfang a few percentage points, but we've found the the DPS loss is easier to cope with than the extra damage that the Marked person will take (especially with only 2 healers) or the increased rate at which Saurfang will gain Blood Power. Most of the time we can kill him before a second one gets cast, if not soon after.
Conventional wisdom says blow Heroism/Bloodlust when he frenzies, but we like to do it right at the beginning of the fight. Specifically because we know we won't be short a person and we have 7 dps (since I'm in cat) for that first 20 seconds or so. We can usually knock him down about 12% super-fast that way.
After Saurfang is dead, there's a pretty cool lore moment that happens, so watch it if you're into that kind of thing.
There's a chest off to the right of his platform that holds the loot.
On 10-man the only useful Bear drop is the Scourge Stranglers. On 25-man you can look forward to Toskk's Maximized Wristguards, the Vanquisher's Mark of Sanctification (which you can use to upgrade an iLvl 251 Tier 10 piece to an iLvl 264 Tier 10 piece once you've purchased one with Emblems of Frost), and Deathbringer's Will, which may or may not be amazing. I'll be discussing the virtues of that trinket in a post sometime within the next week.
As with all my boss strats, I'm writing from the overall perspective of a Bear tank (in 10-man) and what they will need to do. For you Cats reading this blog, I suggest you check out Dinaer's guides on Forever a Noob. They're written for Rogues but are a pretty good guide for melee in general and his gear drop suggestions (with the exception of weapons) will be spot on for Cats. If I have additional insight, I will try to add it in my blog. Here is his Deathbringer Saurfang strat.