Coats the victim in the searing blood of Deathwing. The thick blood will absorb up to 200000 healing done to the target and will cause the victim to cough up blood, periodically inflicting 10000 Physical damage.
Fiery Grip
Tentacle Grips victims, stunning them for up to 30 sec and inflicting 60,000 Fire damage every 3 sec. This effect may be broken by damaging the tentacle significantly. This effect prevents players from being thrown off Deathwing's back.
Absorbed Blood
Absorbs nearby Corrupted Blood residue. The Amalgamation grows more unstable with each Residue absorbed, increasing its damage by 10% and attack speed by 20%. At 9 stacks it will become superheated.
Nuclear Blast
The superheated nucleus of the Amalgamation triggers a massive explosion, inflicting 350625 to 399375 Fire damage to targets within 8 yds. This blast is powerful enough to pry up one of Deathwing's Elementium plates if it is within range.
Seal Armor Breach
When an armor plate is pried up, the Burning Tendons rapidly pull the plate closed, protecting the tendons from further damage and preventing the plate from flying off.
Strategy
This is a one phase fight, where the goal is to remove three armor plates off of Deathwing's back. The fight begins on the middle of his back. There will be exactly four openings where adds will spawn: two on the left side, and two on the right side. With each plate that is removed, two new holes will appear which means more adds will appear as the fight progresses.
The first add will be the Corruption tentacle. Exactly one needs to die quickly because no other add will spawn from the respective hole until the tentacle is dead. Killing more than one tentacle will cause you to be overrun by the adds that spawn from each one.
Each remaining tentacle can cast Searing Plasma, which absorbs a massive amount of healing. Healers will need to heal any player who gets this to remove the debuff quickly. The Corruption tentacle also uses Fiery Grip, which stuns a player and deals periodic damage for up to 30 seconds. Damaging the tentacle for 20% of its health causes it to break its grip.
The next type of add is the Corrupted Blood. These look like little red slimes. They only have two abilities. First, when one dies, it casts Burst, which does a little bit of AoE damage to the raid. After it is dead, it'll leave a Residue and eventually respawn.
The third add is called Hideous Amalgamation. In normal mode, it doesn't do a lot of damage. However, it is the way you remove Deathwing's armor plates. Whenever a Corrupted Blood uses Residue, the Amalgamation can soak it gain the Absorb Blood. This gives the add a stacking buff that does 10% more damage and increases attack speed by 10% per stack. Once the add is at 9 stacks, it'll gain Superheated Nucleus. This will do a lot of periodic AoE damage to the raid, and when the add dies, it'll cast Nuclear Blast. Get the boss to 10% health before allowing it to get the 9th stack then position it right next to the armor plate. The Nuclear Blast will open the armor, exposing the Burning Tendon. Players should move away from the blast or be one shot.
If done correctly, the plate should pry up and expose a Burning Tendon. The Tendon will cast Seal Armor Breach. The raid will have a very short amount of time to kill the Tendon. If successful, the armor plate will fly off and expose two new holes. If unsuccessful, the plate will close, and you will have to repeat the process which will likely cause a wipe. DPS should save all DPS cooldowns for the burning tendon.
The last thing to note is that if the entire raid is ever on the left or right side of Deathwing's spine, he'll use a Barrel Roll to get rid of all players. To counter this, the raid can stand on one of the exposed holes, as long as there isn't a Corruption Tentacle. This will give the player the debuff Grasping Tendrils, which will prevent them from flying off. It's important that all players get this, or they will die and cannot be resurrected. It is recommended that you force Deathwing to roll after each plate is removed since there will be a lot of adds. The Barrel Roll will also remove any adds up that are not gripped as well, so this is a useful mechanic to clean up adds if we get overwhelmed and reduce raid damage.
Heroic Strategy
For the heroic mode, there are two new mechanics to be aware of. First, when a Hideous Amalgamation dies, regardless of the number of stacks, it'll cast Degradation, which permanently reduces the raid's maximum health by 6%. This stacks up to 15 times. This means is we can only kill an add when it has 9 stacks. If we kill any others too soon, the raid's health will get too low to survive any major damage.
The second difference is that the Hideous Amalgamations will cast Blood Corruption to the raid. There are two types:
Both of these can be dispelled. If so, the Blood Corruption will jump to another player and has a chance to mutate into the other one. For example, if a player has Blood Corruption: Earth, and it is dispelled, another player will get it, but it can be either Blood Corruption: Earth or Blood Corruption: Death. Because of this have one healer dedicated toalways dispelling Blood Corruption Death and NEVER dispel Blood Corruption:Earth.The rest of the encounter plays out similarly to normal mode. Your raid will likely not be able to kill a burning tendon in one phase so it is important to kill it in two tries or else it is a wipe. For tentacles All DPS should be used on the first plate (and every time possible thereafter), potions on the second, and bloodlust on the third. Also tank the amalgamation at the same side of the armor plate each time since there are now two different tendons that can be exposed per armor plate. Our raid uses the right tendon every time.
On the third armor plate there will be so many bloods that an off tank (or two) will need to start rounding up and kiting the bloods. It is important to do this because you save a lot of random raid damage and get them out of residual AOE damage. The kiting tank should do their best to not get hit by the oozes, a warrior is the best suited because of their mobility. The last plate is hectic so prepare to use CDs as needed and stay focused and you should be able to get through it. Bloodlust will help a lot with the damage and healing just keep executing correctly for the win.