How to kill Blackthorn?

Killing Blackthorn on the Gunship seems to be the most hectic and the most troublesome for everyone I have raided with this far. What are all the mechanics in detail and how do we deal with all these things to create the most stress-free and easy kill?

This is Normal Mode and LFR only. Heroic has the same abilities plus a few extra

The Warmaster Blackthorn encounter is a two phase fight. Phase one is all about add control. Phase two is dps race while watching your positioning so you don't make your healers job harder.

Phase 1:

There are four types of adds. (Three in LFR)

1. Twilight Assault Drakes
2. Twilight Elite Dreadblades
3. Twilight Elite Slayers
4. Twilight Sappers (Not in LFR)

During this phase Goriona(The drake that Blackthorn is riding) will cast Twilight Onslaught. When this ability is cast you will see a purple swirling void zone on the ship. This ability will be used roughly every 35 seconds. Once the projectile hits the ground it will cause a large amount of damage (1,500,000 in LFR, 800,000 in 10-man, and 2,000,000 in 25-man), which is split between all players (standing in the void zone) and the gunship. You will want most (if not all) of your raid members standing in this zone to make it healable and to protect the ship from extra damage.

The Twilight Assault Drakes will drop off the other adds and then they start firing Twilight Barrage (A similar ability to Goriona's attack but smaller and less harmful). These should be dealt with the same way as Goriona's attack. These drakes should be focused down by your ranged members.

The Twilight Elite Dreadblades and the Twilight Elite Slayers are melee adds and should be tanked. These should be focused on by your melee dps. These adds will charge random players dealing damage to every player in their path. The Dreadblades cast Degeneration, which is a frontal cone attack that deals a moderate amount of shadow damage, and places a DoT on the affected players (lasts for one minute and stacks). The Slayers cast Brutal Strike which is identical to Degeneration except it is physical damage instead of shadow damage. The abilities are cast every 7-20 secs. The only players that should be hit by these are the tanks and they should swap mobs to avoid stacking the debuff too high if you dps is too low.

Twilight Sappers (10 and 25 man normal NOT LFR) are adds that focus entirely on damaging the gunship. After they are dropped off they will go invisible and reappear a few seconds later. They will run to the back of the ship and cast Detonate if they reach it. This deals 20% of the ship's maximum health in damage, and also damages players within 8 yards of the explosion.

Phase 1 is all about add control. Survive 3 waves of adds and phase 2 starts. Tanks pick up Dreadblades and Slayers. Tanks face them away from the raid. Watch for Twilight Onslaught and Twilight Barrage. Whenever a sapper lands all DPS should focus them down. They can be slowed, stunned, and death gripped. You can possibly ignore the last sapper if you dps is high enough and the ship has enough health left to survive the explosion. When the Twilight Assault Drakes are within range of your ranged DPS they need to switch to them and kill them.

Priority for adds:

1. Twilight Assault Drakes (when they are close enough to be damaged)
2. Twilight Sappers (As soon as they land, unless you are ignoring them)
3. Dreadblades and Slayers (Focus on one first, then the other)

Phase 2:

Goriona and Warmaster Blackthorn.

Goriona has one ability during this phase: Twilight Flames. This launches a ball of flame at a random player, dealing massive damage at the location and leaves flames on that spot for a short time. Don't stand in that void zone. Ranged DPS must focus her down asap. At 25% health she will fly away leaving the encounter.

Warmaster Blackthorn has four abilities during phase 2.

1. Vengeance is an enrage that Blackthorn gains throughout the phase. He deals 1% increased damage for each 1% of his health that is missing.
2. Devastate is a sunder armor effect that lowers the tank's armor by 20% and deals damage with each application. The debuff lasts for 30 seconds and stacks (thus requiring a tank swap).
3. Disrupting Roar deals a moderate amount of damage to all raid members and silences all raid members within 10 yards of the boss for 8 seconds. The ability is cast roughly every 20 seconds so casters need to remain further than 10 yards away from the boss
4. Shockwave is a frontal cone attack that deals massive damage to anyone in front of him and stuns them for 4 seconds. This ability is used roughly every 25 seconds. It is cast at a random raid member so be sure you are not in the path.

Phase 2 is a lot less chaotic. Tank picks up Blackthorn and moves him to the center of the ship. Melee dps stay on Blackthorn the whole time and ranged dps brings Gariona to 25% health asap. Move out of Goriona's fire. Once Goriona leaves everyone focuses on Blackthorn. Spread out around him to help with avoiding shockwave (You can see the visible graphical effect on the ground). Melee can usually just step through the boss quickly and then get back behind him after he is done. Casters should stand further than 10 yards away from the boss at all times if possible. The tanks will take increased damage as the fight goes on. Healing can get intense toward the end of the fight.

Learning phase one is the hardest part of the fight. Practice makes perfect. Good communication from raid leaders in vent is a great help on the fight. Call out kill orders, void zones, and shockwaves and you should be downing him with no trouble soon!

Have fun!