FFXIV Heavensward Guide :The Singularity Reactor Primal Fight
This fight is technically a Primal, but different as they are summoned using the bodies of the Archbishop and the Heavens' Ward. It's based on the summon from FFVII, Knights of the Round. The fight itself isn't difficult, but there is a lot of stuff going on.
1.Ascalon's Might: A heavy-hitting frontal cleave.
2.Ascalon's Mercy: A multi-directional conal AoE.
3.Ancient Quaga: A room wide AoE dealing moderate damage.
4.Lightning Storm: Randomly targets three people with a lightning attack.
5.Meteor Rain: Places an AoE circle on random targets. It seems as the fight progresses it targets more people.
6.Knights of the Round: Summons other knights to use their special abilities. These are easy to dodge even if you're not sure what the knight does.
7.The Dragon's Eye: Buffs King Thordan.
8.The Dragon's Gaze: You need to look away during this attack. Just turn your character around, it inflicts terror and vulnerability up if you don't turn away.
9.Chaos Phase: I like to refer to this as Chaos phase because there is so much happening, it's almost impossible to track everything. What you need to know in this phase I'll detail here. Ser Janlenoux and Ser Adelphel need to be killed to progress the phase. They both use the skill set of Ser Adelphel so nothing new. Comet Circles need to be killed, before their comets hit the field. Then kill the Meteor Circle in the middle.
10.Light of Ascalon: After the Meteor Circle goes down, Thordan will reappear and bombard players with Light of Ascalon. It does negligible damage and knocks players back.
11.Ultimate End: After the Light of Ascalon spam, all the knights come together with Thordan to use Ultimate End, a room wide AoE doing considerable damage. After this, just burn Thordan down. He just wildly swings his sword around so there's nothing left but to kill him.