I spent a long time trying to beat the old WR, and I kept falling one second short. I couldn't figure it out? I was starting the fight by reducing the boss to 0.1% hp within seconds, and I was faster on every add phase. It should be an improvement!

Then I found the difference. The old WR was skipping Thordan's "Ascalon's Mercy" by using the strongest available attacks first. The secret is the spell "Both Ends". It is an instant cast, but it is suspiciously extra fast. The damage is assigned at the start of the animation; kind of the opposite of "Being Mortal" which, despite also being an "instant cast", doesn't assign its damage until several seconds later. Armed with this knowledge, and Endwalker blue magic, I devised a rotation that skipped not only "Ascalon's Mercy", but also "Knights of the Round" and went straight to "The Dragon's Eye"! A huge improvement in the first 15 seconds!

After the opener the rest of the fight is an autoscroller. It's cutscenes. I blow up the adds as fast as possible, emote a bunch, and spin the camera around to make the fight look cool.