NB: The Cataclysm strategies are based on a mixture of beta reports and may or may not bear any resemblance to the fight on Live.
If you spot major differences, post them in the comments and I can update the strats. I’ll be updating these myself as my guild begins raiding in Cataclysm.
Tanking: Two tanks required for Phases 1 and 2.
The tank on Feludius needs to get out to range and back in again relatively quickly.
Healing: In Phase 1 healers need to be watching for people with Frozen Blood, who will need massive focused healing and maybe cooldowns.
In Phase 3 the tank on Arion will need cooldowns when he Disperses to mitigate the Lightning Blast.
In Phase 3, they will need to look out for the person or people afflicted by the Gravity Crush, who will also need focused, quick healing.
Positioning: The raid will be split into two teams for Phases 1 and 2.
In Phase 3, melee will follow the boss around the room while ranged will stand in the middle of the room.
Buffs: Fire, Frost and Nature resistance are needed, as is an armor bonus for Terrestra’s heavy physical damage.
Defensive cooldowns need to be used for a few abilities.
Phase 1: Waterlogged – Caused by being caught in Feludius’ Waterbombs’ splash. Removeable by running through the fire trail left by Ignacious.
Frozen Blood – Anyone with this debuff will need massive healing and maybe cooldowns for 10s (~80,000 per 2 seconds) to survive.
Phase 2: Lightning Rod – Anyone with this debuff must move away from other players, or the raid must move away from them. They will attract the next Chain Lightning cast.
Phase 3: Gravity Crush – deals 9% of maximum HP per 0.5s for 6s (108%) plus falling damage. Needs very quick healing.
HP: Feludius and Ignacious: 21,000,000 HP (Unknown on 10-man)
Arion and Terrestra: 14,500,000 (Unknown on 10-man)
Bloodlust: Phase 3 is a DPS race, so save it for then. Either at the beginning of the phase or when DPS cooldowns are ready.
This fight consists of three phases. In the first two you fight pairs of Twilight Cultists who have become elementals: Feludius and Ignacius, Arion and Terrestra; the final phase is against a single boss: the Elementium Monstrosity.
In each of the first two phases the phase ends with both elementals despawning when any one of them reaches 25%. They should all be brought to as close to 25% as possible though, because the Elementium Monstrosity in Phase 3 spawns with the combined HP of each of the bosses when they despawned, and Phase 3 is a DPS race.
Phase 1 – Feludius and Ignacious
Ranged DPS should be on Feludius (water/frost), standing spread out at around 15-20 yards range. This is to allow you to run out more easily when Glaciate is cast (3 second cast). Glaciate deals 200,000 Frost damage to the raid, but the damage decreases dramatically the further out you are. Max range is not advised though, because of Heart of Ice (see later).
The other effect Glaciate has is to freeze the blood of anyone afflicted with the Waterlogged debuff, which is caused by being caught in the 6-yard splash of the Waterbombs Feludius throws at random players. Frozen Blood stuns and deals 80,000 Frost damage per 2 seconds for 10s [some reports say 20,000, which is healable. 80,000 seems unhealable though].
If you get Waterlogged, you should immediately run to the fire trails near Ignacious which will remove the debuff. You do not want to be caught by Glaciate while you have Waterlogged, although it might be inevitable, in which case healers need to be paying attention.
Heart of Ice is a Magic debuff cast on a random player which deals increasing Frost damage every 2 seconds until dispelled. This damage starts at 2,000 and doubles each tick.
[The following may be Heroic only]
However, the player with Heart of Ice also gives nearby players a buff (Frost Imbued) which increases the damage they do to Ignacious by 10% per stack for 30 seconds. Each tick of Heart of Ice adds a stack. The player with Heart of Ice needs to run to the other team as quickly as possible to get as many stacks as possible onto them before the Heart of Ice damage becomes unhealable and it needs dispelling. Swapping the DPS teams once Heart of Ice has gone off might be a better approach, depending on whether or not the melee can run away from Glaciate reliably enough. Needs experimentation
Melee DPS should be on Ignacious. He has an equivalent ability to Heart of Ice, called Burning Blood. As with Feludius, the afflicted player should run to the other camp to spread the Flame Imbued buff as quickly as possible before needing to be dispelled.
Ignacious’ final ability is the most important one. He will cast Aegis of Flame on himself, which absorbs 1,000,000 damage and prevents him being interrupted. As soon as he casts the Aegis, he will start channelling Rising Flames which deals increasing fire damage to the raid until the Aegis is broken and he is interrupted. Having decent stacks of the Frost Imbued buff is important to break the Aegis as quickly as possible.
Both bosses should be taken to just above 25% before one is taken under and they despawn, to be replaced by Arion and Terrestra and Phase 2 begins.
Phase 2 – Arion and Terrestra
This phase is all about the raid picking up the right debuff at the right time to mitigate the one-shot mechanics each boss has.
DPS splits again: melee are best assigned to Terrestra and ranged to Arion, since Arion is a lot more mobile. It might be that DPS needs to alternate to deal with Terrestra’s Harden Skin before he can kill people, so be prepared to alter the strategy somewhat. [Maybe on heroic?]
Arion’s big one-shot ability is Thundershock, which will deal 150,000 Nature damage to the raid, but the damage is reduced to manageable levels by gaining the Grounded debuff from stepping into the Gravity Well void zones Terrestra puts down. Don’t stay in the Gravity Wells though, because being in one causes Gravity Core, dealing 10,000 damage per 2 seconds.
Terrestra’s one-shot ability is Quake, which deals 150,000 Physical damage to everyone, unless they have the Swirling Winds debuff obtained by moving into the Violent Cyclones Arion creates with his Call Winds ability.
Only this buff will work – Levitate will not work. Opportunities for mischief abound as both effects look superficially similar!
Terrestra’s other abilities to watch out for are Eruption, which creates spikes which knock anyone within 4 yards of the target up into the air, dealing 50,000 Physical damage (ignores armour), and Harden Skin which increases his Physical damage dealt by 100% and absorbing 50% of damage taken until it absorbs 650,000 damage (i.e. the raid has done 1,300,000 damage), at which point it will shatter, damaging Terrestra. This needs to be broken as quickly as possible.
Arion’s other abilities are marking a player as a Lightning Rod, whom players need to run away from quickly so that the ensuing Chain Lightning does not hit them, and Disperse, where Arion will disperse into wind and reappear somewhere else in the room, casting Lightning Blast on the tank for 90,000 Nature damage immediately afterwards. Defensive cooldowns should be used to mitigate this.
Again, both bosses should be taken down to as close to 25% as possible before taking one under to enter Phase 3.
Phase 3 – Elementium Monstrosity
The Elementium Monstrosity phase is similar to the Grobbulus encounter in Naxxramas, but without the adds. This phase is a DPS race, because the raid-wide Electric Instability aura the boss has increases in damage until he dies.
The ranged DPS should be stood in the middle of the room to minimise their movement, while the melee should obviously follow the boss.
The Monstrosity should be picked up and taken to the edge of the room, where he will be kited slowly around to move him out of the Liquid Ice patches he will drop. They will grow as long as the boss stands in them, so moving him out quickly is vital. Anyone standing in the patch takes 5,000 Frost damage per second.
The raid need to watch out for, and run away from, the Lava Seeds the Monstrosity will scatter across the room, which will explode for 50,000 Fire damage.
Healers will need to be on the lookout for players caught in a Gravity Crush, which will lift them off the ground and deal 9% of their max HP as Physical damage every 0.5s for 6s (108%) and then drop them for falling damage.
Just avoid the bad and pull out all the stops on DPS, and get him down before the Electric Instability becomes unhealable.