All right, we've had a few other topics on our minds over the past week, but time to get back to our DK perspective on TOC! The Faction Champions are the famed "PVP in PVE" encounter of the Lich King!
As I'm sure you know, in this raid you'll get mobs of the opposite faction with typical class abilities and a decent-sized health pool. The AI is relatively sophisticated but also predictable on this fight. As you know, they'll crowd control (cc) your raiders, heal each other, and on heroic even break crowd control. It is a challenging fight particularly if you don't pvp at all, and heavily emphasizes your raid's crowd control abilities - something recently debated quite a bit on various blogs.
Pull: There are many ways to do this pull, but the most popular by far is the Death Grip - putting you front and center! If you have two DKs, you may even try to double DG the kill target across the arena, but that often fails if there's a shaman in the enemy group due to grounding totem. We tend to save extra DGs for crowd control. Make sure to have full runic power before the pull as intense burst on the first target is crucial. If Army of the Dead is available, summon them before the pull - they're very useful - even if they break cc in my opinion. They'll be targeted by the champs, they'll help distract healers, provide dps, and so on. Pop all your cooldowns without even waiting for attack power procs - just get the burn on the skull!
You will have one of two primary roles on this fight:
1) Zerg dps
2) Crowd control/distraction
1) If you're on dps burn team, pop every cooldown and don't hold back. Getting the first target down asap is the key to the fight. Do pestilence, however. Pest is smart and won't break cc and can add an amazing amount to your dps - and cause the AI to heal non-burn targets. DON'T Death & Decay. Yes, the dps is nice, but it will break cc. If for some reason you have corpse explode, don't use that either. Howling blast is a no-no. Otherwise, your abilities are safe from breaking cc. Well, heart strike will break cc, but I'd still use it as the cc targets are hopefully kept away from your burn target. When I did this fight as blood, I only broke one cc a fight on average, which is pretty insigificant.
2) If you're on cc/distraction, you have several tools. I've done resto druid several times, and warrior/rogue a few as well. On a healer, you'll mind freeze - say, nourish - the first heal. DPS the healer. Then, Strangulate the next nourish (so be careful to save an unholy rune or at least blood tap). Then mind freeze the next. Then, while mind freeze is on cooldown, move several yards away from the healer in the opposite direction from the burn target. When the mob starts to cast nourish, death grip them to you. They'll be interrupted but not locked out, but they'll focus on you for a moment and are hopefully out of range of the burn target. By then mind freeze should be up. Rinse, repeat. If on a melee dps, death grip them out of the raid and icy chains them. DPS them which sometimes gets them mad. On normal, taunt works somewhat. Icy chains with every frost rune. Death grip on every cooldown - if you know you'll be doing this, spec into reduced death grip cooldown, and maybe even into desecration to slow them down. If you have a spare moment, you may toss a little dps at the burn target.
Keep yourself alive! Use anti-magic shield on every cooldown. Save Icebound Fortitude for when you're getting dps'd hard. Run away when melee focus on you - strafe is best. Icy chains any melee pursuing you. Eat a healthstone, use defensive cooldowns (bone shield etc), use profession or race abilities if you have them (gift of the naaru, herbalism heal, etc). Don't die, but don't use them all at once unless you must. Just give your healers time to start healing you.
Heroic: If you're on heroic, the fight is significantly tougher! The champs have more health, hit harder, and play dirtier! They'll break out of cc with 'trinkets,' and they're untauntable. Your role will still be one of the above, however. Just do it better! There's lots of ways to do these fights. On normal, I've successfully done in multiple ways. On heroic, the only success we've had is cc the healers and kill the top dps. Your cc has to be spot on, and your dps must burn fast, but if you do, you have a chance!
Lately I've seen my dps rocket up on this fight. We DKs have lots of survivability, and lots of burst. Pestilence adds a lot to dps and I've seen a lot of my recent parses over 8k.