First off to find the place (to unlock your Looking for Dungeon), inside Blackrock Mountain, if you use the normal path to get to Blackrock Spire, not the jumping on ledge way to avoid mobs way...    By the summoning stone, go in there, turn right instead of left.

Rom'ogg Bonecrusher

• Quake - Slams the ground doing 9000 physical damage to all enemies over 3 seconds.
• Skullcracker - Deals 95,000 to 105,000 damage to all nearby enemies
• Wounding Strike - Does 125% weapon damage and leaves the MS effect (-25% healing) for 6 seconds

Notes:

• Some high spike damage to tank, use CDs
• Quake is like the goo explosion on Rotface, sorta, where you were standing is where the damage will be, so move from that spot
• Skullcracker is cast just after he pulls everyone close and chains them.   Target those chains and kill them to free yourselves, then run, or die.

Corla, Herald of Twilight

• Aura of Acceleration  - Increasing movement by 50% and attack speed by 100% to nearby allies
• Dark Command - Causes a target to flee for 4 seconds, and does 28000 shadow damage over the duration

Evolved Twilight Zealots

• Blood of the Evolved - Coats their weapons, granting 30% chance to deal 2975 to 4025 physical damage when bleed effects damage the target
• Force Blast - Inflicts 6300 to 7700 to target, knocking them back
• Gravity Strike - Inflicts damage equal to 70% of the target's HP, and briefly reduces their AP by 1000
• Grievous Whirl - Deals 7125 to 7875 physical damage and a bleed that does 750 damage every 2 seconds til fully healed
• Shadow Strike - Appears behind enemy and strikes for 35000 shadow damage

Notes:

• The Netherspite fight
• Starts with 3 adds, harmless but big purple beam will turn them into lethal Evolved Zealots
• Standing in the beam will prevent transformation
• Standing in the beam gives you a debuff that stacks to 100 where you get MC'd.
• Buddy up, alternate taking the beam to prevent transformation and being MC'd or do some beam dancing in and out like Netherspite
• Allow the Zealot to become Evolved one at a time and kill it
• Repeat til all dead
• Kill boss

Karsh Steelbender

• Burning Metal - Inflicts fire damage to target, 1000 fire damage per stack of Superheated Obsidian Armor
• Heat Wave - Inflicts 1000 fire damage to nearby enemies per stack of Superheated Obsidian Armor
• Obsidian Armor - Nearly impervious to all damage at normal temperatures, reduces damage taken by 99%
• Superheated Obsidian Armor - Loses damage mitigation properties, but deals additional fire damage per stack, increases damage taken by 10% per stack, stacks to 100

Notes:

• A bit of an Ignis fight, well his adds maybe
• There's a big fire/lava pit in the room, take him in there so you can start doing damage
• But not too long or he starts killing everyone with the stacks of fire damage, 5-6 stacks seem to be good
• When his stacks fall off, the lava crate ignites in flame, don't stand on it

Heroic:

• Go 10-12 stacks
• Elementals spawn when the stacks fall off
• Kill those first before starting dps cycle back on boss (i.e don't get more stacks)
• They drop fire void zones to not stand in

Beauty

• Berserker Charge - Charges, knocks back, does 7863 to 9137 physical damage
• Flamebreak - 6013 to 6987 fire damage to nearby enemies, knocks back 
• Magma Spit - 3400 to 4600 fire damage to enemy, sets them on fire causing additional 4000 fire damage every 3 seconds, explodes when removed
• Terrifying Roar - Causes enemies nearby to flee in fear for 4 seconds

Notes:

• Charges farthest person
• Debuff that explodes, so stay away from people
• Has 4 pups with her, can be pulled before and killed, but Runty's death will cause her to Berserk
• Pups also able to do fire breath leaving a fire puddle (void zone) on the ground doing 2K per second, stacks per pup.

Ascendent Lord Obsidius

• Stone Blow - Attack that increases melee damage by 50% and knocks target down
• Thunderclap - 7500 to 8500 nature damage to nearby enemies, slowing movement attack cast speeds by 35% for 8 seconds
• Transformation - Possesses one of his shadows
• Twilight Corruption - Inflicts 4000 shadow damage every 2 seconds for 12 seconds

Notes:

• Starts with 3 shadow adds, they do a 100% healing reduction on their target
• They must be kited / rooted / snared, immune other CC's, and threat is based on last one to hit them
• Obsidius randomly switches places with one of the shadows wiping all threat, so don't kite too far or you could die