Originally Posted by Aliena
Hello and welcome to TankSpot's Guide to Blackrock Caverns! My name is Aliena, and in this video I'll show you all you need to know about the new five-man instance released with Cataclysm.
Blackrock Caverns is located in Blackrock Mountains, a little ways down from Blackrock Spire. You're faced with five bosses in this instance. The first boss awaits you just a little way after starting the instance, in the Chamber of Incineration. His name is Rom'ogg Bonecrusher and he's a big old level 82 elite ogre. Make sure to clear the room of trash before you engage him!
Rom'ogg puts a mortal strike ability on your tank that reduces healing effects by 25% and also has a quake ability he uses on everyone in melee range, but the damage on that is low so you don't have to worry about it much. His signature ability is The Skullcracker - Rom'ogg will periodically pull every party member into melee range, put something called Chains of Woe on them and channels his Skullcracker ability.
To avoid it, your DPS needs to kill the Chains of Woe and everyone needs to move about 15 yards away before his channel ends. Everyone remaining in close range will get hit and potentially die.
After you defeat Rom'ogg, you release Raz the Crazed. Don't worry, he's on your side and he'll help you clean out a big part of the trash to come. Let Raz run ahead and clear whatever trash is left.
The second boss awaits you a little ways down from the bridge in the Halls of Awakening, her name is Corla, Herald of Twilight. She's also a level 82 Elite and comes with a twist. As you approach her, you'll see that she has two minions. As soon as you engage her in combat, the dragon overhead will channel a beam to those two stationary minions, giving them a buff. When their buff reaches 100 stacks, they turn into enemy dragons that will join in the fight. To avoid this, have two of your party members interrupt the beams.
They'll take the stacks instead, so make sure not to let it stack up to 100. If you have to, cycle people in and out. Corla herself doesn't do very much. She has a dispellable fear that she'll place on a random party member and an aura that buffs the minions should you let them evolve into dragons - but again, the point is not to let that happen.
Raz will help you clear some trash on the way to the third boss again, but quite a few trash packs await after Corla. Eventually you'll reach a fiery hallway with frozen slimes - this is the Twilight Forge, where you fight Karsh Steelbender. Before engaging Karsh, clean out the fire elementals one by one. They hurt and apply a stacking fire resistance debuff, not something you want up during the fight. The slimes can be completely ignored.
To fight Karsh, you have to use the environment to your advantage. After engaging him, everyone should run to the middle ring around his forge (not the grid, occasionally fire will spout of it during the battle). You'll notice he has a buff called Obsidian Armor, making him virtually invulnerable unless you drag him over the center of the forge, melting his armor in the process.
Don't keep him in the center for too long though - 5 seconds is a good medium to shoot for - since for every second he spends in the center, he'll apply stacking AoE fire damage to everyone in your party. Do a little dance with him, 5 seconds in the fire, 5 seconds out of it, rinse repeat, and he's an easy opponent.
Again quite a bit of trash after Karsh, but eventually you'll reach an optional boss in a side hallway called Beauty's Lair. Vanilla WoW players will catch the reference in this fight. Beauty comes with 4 adds called Buster, Lucky, Spot and Runty. Runty is hiding all the way in the back of the Lair, and for good reason! Don't attempt to kill him, as this greatly enrages Beauty. You'll regret it.
The other three adds can be pulled ahead of the battle though, and once you take them out you're left with Beauty. She hits fairly hard and has a Berserker Charge, that knocks the target back and inflicts damage. She also has an AoE fear, so if you have tremor totems or fear wards, this is a good battle to use them. She throws out some fireballs that you should move out of, but it's a very easy fight if you leave Runty alone.
The last boss is a little ways out from Beauty, located in the Scar of the Worldbreaker. His name is Ascendant Lord Obsidius, and while all that sounds intimidating, he's really all bark and no bite. Have someone kite them around, as they inflict a mortal strike ability. If your tank tanks all three, you won't really be able to heal him. They don't deal much damage, but occasionally Obsidius will change places with one of his minions, resetting the threat table in the process.
Alternatively, you can share threat by having your DPS keep high threat on the minions and having them pull them off your tank when he needs a heal. This really depends on how geared and organized your group is. Lastly, Obsidius has a debuff called Twilight Corruption - this is a magic dot and can be dispelled.
After he dies, you've completed Blackrock Caverns. Congratulations!