The name itself is pretty straight forward with one elemental AoE on a 20 second recast and needs the mage confidence debuff.
At certain time intervals the name will port to the center area and pop a bubble the size of the circle in the center and clear all effects, including the confidence debuff. It will have a reflect that one shots anyone who tries to cast ANYTHING, including debuffs. After about 20 seconds it will depop the bubble and be hittable again, make sure to get the confidence debuff in again.
Adds will also spawn with the name 'a toxic elemental'. One will spawn the first time, two the second time, and three every time after that. Each one of these adds has three AoE abilities: Obsidian Shards (moderate piercing dmg), Venemous Cloud (incurable Noxious stifle with low poison dmg), and Stunning Shards (curable arcane stun with low magic dmg DoT). On top of all this when an add dies it will spawn a green smoke area on top of where the add died. Standing in this area will inflict high poison dmg by the name Toxic Tremor. If the named is around one of these smoke areas it will gain a buff for 12 seconds to increase dmg output.
The time intervals are as follows: 35 seconds after pull; 70 seconds after first port; 115 seconds after second port; 150 seconds after each successive port until mob dies.
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Challenge Mode
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The fight is basically the same in HM except if you get a 4th or 5th spawn of adds there will be 4 and 5 adds that spawn respectively. The raid has never lived through 5 adds.
If your tanks and healers can manage it you can leave adds alive in the 2nd 3rd or 4th spawn. Kill one add in each rotation and the other adds will despawn when the next set pops.