Growing Twilight instability causes 300,000 Shadow damage every 6 seconds, split evenly amongst enemy players in the Twilight Realm and within 30 yards of the target.Every minute that Ultraxion remains in combat reduces the time between arcs by 1 second, to a maximum rate of one arc per second.
Fading Light
Ultraxion sucks the light out of his current target and one random player, drawing them into Twilight over 5-10 seconds. Upon expiration, players in the Twilight Realm instantly die.
Twilight Shift
At the beginning of the battle, Ultraxion pulls all enemies with him into the Twilight Realm where they can bear the full brunt of his powerful Twilight assaults. The Twilight Realm grants players the Heroic Will ability.
Heroic Will
The player's Heroic Will steels the caster's mind to resist the forces of Twilight. This pulls the caster out of the Twilight realm for up to 5 sec, but renders them unable to attack, cast spells, or move while concentrating.
Hour of Twilight
Enemies caught within the Twilight Realm take 300,000 unresistable Shadow damage. Players within the normal realm forcibly enter the Twilight Realm. If Hour of Twilight does not hit a player, the Aspects take the full brunt of the attack, causing a wipe.
Looming Darkness
When struck by Hour of Twilight, powerful waves of energy course through the victim, rendering them more susceptible to the harmful effects of Hour of Twilight. Players instantly die if Hour of Twilight inflicts additional damage to them.
Twilight Burst
If every player stands outside the range of his powerful claws, Ultraxion expels a powerful burst of Twilight energy. This burst inflicts 73125 to 76875 unresistable Shadow damage on all players and increases their magical damage taken by 50% for 6 sec.
Twilight Eruption
After 6 minutes have passed, Ultraxion's instability reaches uncontainable levels and erupts outwards as a massive explosion that destroys all nearby foes and Ultraxion himself.
Strategy
This is the Patchwerk/DPS race/gear check with a 6 minute enrage (Twilight Eruption). which instantly kills everyone. As soon as the fight begins, the boss will use Twlight Shift, where everyone gets pulled into the twilight realm. While you're in the twilight realm, you'll be given a new ability called Heroic Will. This will allow you to leave the realm for 5 seconds, but you won't be able to do anything during that time. You'll need this ability at various points throughout the encounter.
Pro Tip: some addons interfere with the Heroic Will ability properly showing up. Use this macro to remedy the problem: /click ExtraActionButton1
The next thing the boss has is Unstable Monstrosity. The boss will use Twilight Instability every 6 seconds, and the damage is spread evenly among the raid. Every passing minute, on the minute, the boss will use Growing Instability. As a result, the time between Twilight Instability will decrease by 1 second increasing the required healing per second on the raid.
The boss will periodically cast Fading Light on a tank and 3 random DPS (Tank+1 on 10 man). Any player targeted must leave the twilight realm 5 seconds before before the debuff expires, or the player will instantly die. Note that the debuff can be up for longer than 5 seconds, but you need to make sure you leave the twilight realm within 5 seconds of the expiration. After the debuff expires, all threat will be lost, and the player cannot generate any threat for 10 seconds. The off tank will need to taunt when the main tank gets this debuff. The boss' key ability is Hour of Twilight, which happens every minute, on the minute. The boss will cast this for 5 seconds. Afterwards, everyone who is still in the twilight realm will get hit with 300k unresistable shadow damage. Initially, this would mean everyone should get out of the twilight realm. However, at least 3 players must be hit by the ability or else ultraxion will instantly wipe the raid. Choose at least 3 players to stay behind with strong defensive cooldowns. Rogues, fire mages, hunters, shadow priests and paladins are all good choices. If you are short on these classes you can have the raid take a hit with a major cooldown like Power Word:Barrier or Spirit Link Totem.
30% Nerf tip: A Paladin with Glyphed Divine Protection can also survive the Hour of Twilight.
One major problem later in the fight is the extreme amount of raid damage from Unstable Monstrosity. Fortunately, the dragon aspects will be helping out by providing buffs for the healers throughout the fight.
Gift of Life
Imbues one target with the essence of life itself, increasing healing done by 100%.
Essence of Dreams
Imbues the target with the power of dreams. Direct healing done is duplicated and distributed evenly amongst all friendly targets within 50 yards.
Source of Magic
Imbues one target with the essence of magic, reducing the mana cost of all spells by 75% and increasing spell haste by 100%.
Gift of Life priority should go to druids and disc priests but any healer can benefit equally. (spawns around 1:20 into the fight) Essence of Dreams priority should go to shaman and holy priests because they have a lot of direct heals that can duplicate. (2:30) Source of Magic should go to paladins for Holy Radiance or a shaman/holy priests. (Spawns at 3:35)
Tanks will get the Last Defender of Azeroth Buff which allows them to chain cooldowns the entire fight.
Heroic Strategy
There are three key differences to the fight. First players hit with Hour of Twilight in the twilight realm will get the debuff Looming Darkness for 2 minutes. What this means is if you get hit by Hour of Twilight a second time with the debuff, you are guaranteed to die.
The second key difference is that you will need 5 players to get hit with Hour of Twilight each time. However, because of Looming Darkness, you'll need 3 groups of at least 5 players taking the hit. A cooldown must be available for each hit in order for the players to survive.
To handle this you will want to organize a rotation of at least 5 players to get hit by Hour of Twilight every minute. As long as a defensive cooldown is available each time, it should be survivable. Our setups is as follows:
The last key difference is that the boss will select six players for Fading Light instead of the current main tank and a second player. Also, when you're ported back to the twilight realm, you'll get a debuff that makes you take 100% more physical damage for 1 minute. This is in place of not being able to produce threat.
The heroic fight will go the same as normal mode except for when you get to the five minute mark. At that point, the raid is taking an extremely high amount of damage every second. Therefore, you will have to coordinate and chain cooldowns until 5:30, which is when the seventh and final Hour of Twilight. These cooldowns will include the Prot. Paladin four-set bonus, Tranq., Barrier, Spirit Link Totem, chaining Rallying Cry, etc. After Hour of Twilight happens, we can use the Prot. Warrior four-set bonus for the remainder of the fight. If you are nearing the enrage timer it is important to have healers fade out early (to avoid getting lust when the DPS do at the beginning of the fight) and get a bloodlust at the 5:30 mark.
Be Mindful of your macro for realm switching, use proper rotations and do as much damage as possible and this should be a kill