Short Tactic Overview:

1. MT moving Ignis arround, Ignis must not face the raid.
2. Two OT are moving the Constructs into the scorch areas (fire) until they got 10 stacks of Scorch and become molten.
3. When molten, constructs have to be moved into the water and it will shatter if 5,000 or more damage is done in a single hit.
4. From time to time Ignis will grab a player into his Slag Pot, and will be damages for 5k/s for 10s (heroic).
5. Ignis will cast Flame Jets The spell will damage the hole raid for like 8000 and throw all players up into the air. If you cast a spell while this, you will get interuppted for 8s. In addition all tagrets take a debuff dealing 2500 damage per second for 8 sec.

Healing

Holy priests shoudl be assigned for raid-healing. It's a good idea to have Seperendy stacked when Ignis is casting Flame Jets so you cast a PoH direclty on one of the groups when you touched ground again. You should assign which healer is focusing on which groups.
While in air, you can cast a PoM and a CoH.
To have it more easy to find the player who is inside the Slag Pot add the debuff "Slag Pot" to your Grid.