Heroic: Elegon

I will attempt to explain the differences between this and normal mode as best I can here. There aren't many differences, but they are critical.

The first and most important change is that the transparent floor in the middle acts as a giant smoke screen, if you will. If you're outside of it, you cannot target anything within (enemy or ally) for attacking or healing. Likewise, those on the floor cannot target anything outside it. NPCs also have this restriction, which will be important later on.

The DPS check is much higher here, as Elegon has significantly increased health. This makes the spark waves important, since you will need to destroy at least 4 waves (letting the 5 wave/stack go through) to have a likely chance of beating the berserk.

The celestial protectors aren't too different with two exceptions. First, the aoe pulse they start doing at 25% deals MUCH more damage, you cannot afford more than one on the raid per protector. But, as explained above, if the mob is outside the floor when it is pulsing, it will not hit anyone inside. So its a matter of tanks being quick on moving the protector to the outside. However, there is a second problem. The Total Annihilation it casts on death deals 600k damage, and must hit at least some players (1 on 10player, 3 on 25player), or the resulting effect will instantly kill the raid. In addition, being exposed to Total Annihilation will stun any affected player until fully healed, and if they attempt to soak another Total Annihilation in the next two minutes, they will be killed instantly. Therefore, a rotation is required to soak these, which should be pre-determined.

The spark and transition phases are virtually identical to normal. The only noticeable difference being the small adds summoned by the spark puddles hit very hard and need to be cc'd and aoe'd down quickly after the floor comes back up.

The final phase is also the same in concept, but the damage elegon puts out on the raid during this phase ramps up to being very hard to heal within about 30-40 seconds. If you've done the spark phases well, this final phase shouldn't last more than one minute. Make sure to stack in the middle!

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Tactics for 10m (heroic):

Although Wowvocate nicely put together the differences already, I'll repeat them in short before giving an actual tactic.

Differences to normal mode:

• 
  
  
• The inner circle which gives both the Touch of the Titans and the stacking Overcharged debuffs is now, technically speaking, a giant smoke bomb, meaning neither of you can cast something on targets outside the zone while you're in and vice versa.
• 
  
• The add explosion now does a lot more damage (500k) and applies two debuffs (Destabilizing Energies and Destabilized). However, the explosion is susceptible to the "Smoke bomb" effect mentioned above, so you can actually choose who should be hit and who shouldn't. If none gets hit, the raid will be wiped immediately by Catastrophic Anomaly.
• 
  
• As usual, everything hits a lot harder and has a lot more HP.
• 
  

Tactic:

2T2H6DD. I don't really thing any other setup is very viable due to the Energy Charge waves.

To safely beat the encounter, you should be able to

1. 
   
2. Finish the first phase 1 before the third protector spawns.
3. 
   
4. Finish the second phase 1 before the fourth protector spawns
5. 
   
6. Kill at least 5 waves of Energy Charges during the first and at least 4 waves during the second Phase 2
7. 
   
8. Kill all Empyreal Foci roughly at the same time in P3
9. 
   
10. Not get hit by Cosmic Sparks at all (or at least almost not get hit)
11. 
    

Phase 1:
Assign two/three players for the explosions. Many immunity effects do not work, but many classes are able to reduce the damage so much that they do not even get the Destabilizing Energies debuff (e.g. Shadow Priest with Dispersion or Warlocks with Dark Bargain). Your tanks must get used to pulling the adds over the edge at nearly exactly 25% to ensure that they will still die from dots (plus the assigned explosion player and the tank himself) and to make sure none on the inner ring gets hit by the Stability Flux. None of the other players should reset their stack unless he can do so without losing dps (there is a position where you can reset by jumping, but it's rather difficult to find on the later phases).

Phase 2:
After two adds/three adds, Phase 2 begins. While running on position reset your stack and do so at every opportunity (read: after you killed your Energy Charge and helped your neighbour) to help your healers. Get 5/4 waves down. Make it clear beforehand how many waves you'll do and use the final wave to chop of some percent points from Elegon. The main reason for doing less waves in the second Phase 2 is having your most important dps cooldowns in the final phase. So if you're capable to do 9/9 or something, do so, but you don't need to and if you are able to, you probably beat this boss way before me, so why do you read this at all? :-)

Phase 3:
Don't fall to your death and try to kill the foci nearly at the same time. Not only do you get an Achievement, but Elegon gets a casting speed buff for every dead Focus and will spawn adds faster and faster, so if you kill them simultaneously (and still fast) you'll have a lot less adds.
The adds hit HARD, don't ever get hit when you're not a tank and don't get hit often as a tank. They're susceptible to slow effects, our tactic was simply kiting them until elegon realizes it's P1 again, then bomb the living #§%! out of them on the plattform.

Final phase:
Don't reset your stacks at all unless you can do so without losing dps/hps or your life (the Vortex on the outside hits extremely hard). If you did everything right to this point, Elegon will have about 30% HP and taking more than double damage, so just throw BL/Heroism and finish him. We were actually all clustering near the boss to help out the "area healer" holy paladin.

While the fight itself is very nice imho, it is comparatively easy now that every raid has gear from HoF/ToES. We were able to beat it with only 10 tries, a lot less than Stone Guard, Feng and Gara'jal.

Have Fun!