Blackwing Descent: Nefarian

The final and epic fight of Blackwing Descent. Not only do we fight the huge Nefarian, we also battle our old friend Onyxia. Killing both of Deathwings children again in one battle is really going to piss him off.

This battle is long and complicated (as expected from the final boss in a raid). Split into three main phases.

Phase 1: The raid will jump into the arena to commence battle with the cuddley Onyxia. The arena is a large circle with three large pillars spread equally around. 30 seconds into the fight Nefarian realises Onyxia is as rubbish as always and will land in the centre of the arena to help her. When the two bosses closer than 60 yards apart they gain 100% haste. Abilites:

Onyxia: 6.6M/24M HP on 10/25. Slowly buids up lightning energy making her more powerful. This provides a soft enrage.
Electric Discharge: When the lightning orbs on Onyxia's sides are glowing inflicts 19500 to 20500 Nature damage per second to enemies on Onyxia's sides. Damage increased by Onyxia's lightning charge level. Can be avoided by line of sight behind the pillars in the room.
Shadowflame Breath: Inflicts 25,000 Shadowflame damage to enemies in a cone in front of the caster every 0.5 seconds for 1.5 seconds. Also ressurects Animated Bone Warriors in the area of effect.
Cleave: Inflicts 110% of normal melee damage to an enemy and its nearest allies.
Tail Lash: A sweeping tail strike hits all enemies behind the caster, inflicting 15750 to 20250 damage and stunning them for 2 sec.
Children of Deathwing: Nefarian and Onyxia attack 100% faster when they are within 60 yards of each other.

Nefarian
Hail of Bones: Nefarian will cast this six times in phase one before landing, each time spawning an Animated Bone Warrior and doing 23987 to 26512 Shadow damage to nearby enemies.
Cleave: Inflicts 110% of normal melee damage to an enemy and its nearest allies.
Shadowflame Breath: Inflicts 25,000 Shadowflame damage to enemies in a cone in front of the caster every 0.5 seconds for 1.5 seconds. Also ressurects Animated Bone Warriors in the area of effect.
Tail Lash: A sweeping tail strike hits all enemies behind the caster, inflicting 15750 to 20250 damage and stunning them for 2 sec.
Children of Deathwing: Nefarian and Onyxia attack 100% faster when they are within 60 yards of eachother.
Nefarian's Lightning Machine: If DPS'd during phase 1 will cast Electrocute: Generates a massive bolt of lightning that strikes the ground, inflicting 60000 Nature damage on all enemy targets.

Animated Bone Warrior: 6 are spawned before Nefarian lands. Have an energy bar that depletes over time. When bar is deplete they deactivate. Bar is filled by either dragon's Shadowflame breath. Too much life to kill. Abilities:
Animate Bones: Shadowflame energy animates these bones, taking 2 energy per second.
Empowering Strikes: Melee and Ranged attacks empower the caster, increasing all damage dealt by 100%. Stacks infinitely.

Phase Two: Starts when Onyxia is killed. Nefarian flys above the arena and fills it with magma. The raid needs to swim in the magma until it gets high enough for them to jump onto the top of the pillars. A Chromatic Prototype is on the top of each pillar and needs to be killed> therefore so the raid must split.

Magma: Swimming in Magma deals 5,000 fire damage per second. Increases damage taken from Magma by 2000. Stacks.

Nefarian:
Shadowflame Barrage: Spammed on the raid the whole of phase 2. Inflicts 22500 to 27500 Shadowflame damage to an enemy with a 1 yard splash radius.
Shadow of Cowardice: Inflicts 30000 Shadowflame damage to an enemy and increases Shadow damage taken by 100%. Appears to only be used when trying to exploit the encounter.

Chromatic Prototype: 2.6M/8M HP. Does not move but constantly casts Blast Nova.
Blast Nova: 3050 to 16950 Fire damage to all enemies every 2 seconds for 30 seconds. Interruptable.


Phase 3: Starts when the Chromatic Prototypes are killed or 3 minutes have passed into Phase 2. The Magma falls and Nefarian lands back in the centre.

Nefarian
Cleave: Inflicts 110% of normal melee damage to an enemy and its nearest allies.
Shadowflame Breath: Inflicts 25,000 Shadowflame damage to enemies in a cone in front of the caster every 0.5 seconds for 1.5 seconds. Also ressurects Animated Bone Warriors in the area of effect.
Tail Lash: A sweeping tail strike hits all enemies behind the caster, inflicting 15750 to 20250 damage and stunning them for 2 sec.
Shadowblaze Spark: Creates a shadowy blaze at a nearby location that spreads quickly. It will expand from its starting location in a circular shape and will follow players and speed up if it is touched.
Shadowblaze: Inflicts 35000 Shadowflame damage to enemies within the Shadowblaze. Also ressurects Animated Bone Warriors in the area of effect.

Animated Bone Warrior: These are still present from where they deactivated in phase 1. Can still be ressurected by Nefarian's breath and in Phase 3 will also be ressurected by the Shadowblaze Spark.
Animate Bones: Shadowflame energy animates these bones, taking 2 energy per second.
Empowering Strikes: Melee and Ranged attacks empower the caster, increasing all damage dealt by 100%. Stacks infinitely.


Tactics
Phase 1:
Tank picks up onyxia and takes her to one side. Raid starts DPSing her. Avoid head and tail. If you are closer than 40 yards to her avoid the Electric Discharge by hiding behind a pillar when the side orbs start glowing.
When the Animated Bone warriors are spawned they need to be kited around until they deactivate. Do not kite infront of the dragons or their breath will reactivate them. They can be snared, slowed etc. Do NOT hit them or they become stronger.
When Nefarian lands the other tank picks him up and takes to the opposite side from Onyxia. Probably best to have them both facing the same way so that the Animated Bone Warriors can be kited where their tails are.
Raid needs to do as much damage to Nefarian as possible in this phase without triggering his Electrocute or running into Onyxia's soft enrage.

Phase 2:
Raid splits up and all spread out as much as possible on the top of the little pillar to minimise splash damage. Kill the Chromatic Prototypes quickly as their damage appears to stack. Best to leave 1 at low health and do as much damage to Nefarian before triggering Phase 3. Probably all ranged should stay on Nefarian during phase 3 and let melee deal with the Chromatic Prototypes, DPSing and interrupting.

Phase 3:
Burn phase. Nefarian will slowly increase the frequency at which he casts Shadowblaze Spark throughout this phase. It starts off small and expands in a O shape until it despawns. The more people it hits the bigger it expands and the harder it becomes to avoid. With multiple active later into Phase 3 they become very difficult to avoid.
The Animated Bone Warriors will be activated by the Shadowblaze and so multiple will be active throughout the fight. They will need to be kited, slowed, snared etc. The spare tank can help with this.
The tank on Nefarian will probably need to move him to avoid the expanding rings of Shadowblaze and allow melee to continue DPSing. Best to kite around the arena but may need to bring in if space is tight.

Looks like fun!