It's Transpose Flare Flare wait Transpose Flare Flare. Yet if you're doing Transpose Flare Transpose then you're doing way less damage since you aren't doing a Astral Fire 3 Flare which gimps your overall damage. Also please use Quelling before Raging.
I prefer to use
Fire 3
Quelling + Raging
Fire 2
Fire 2
Fire 2 (3rd one isn't needed if you have another player that can do their AoE rotation reliably)
Flare
Convert
Flare
MP pot
Swiftcast
Flare
The first full pull in Brayflox is dead and it does way more than your suggested rotation.
Yeah I personally wouldn't recommend it because it's not only an exploit but it's also a gamble that's less efficient to use that the legit ways Black Mages have to Flare already. So trying to shove this exploit method of Flare into people's rotations especially the casual crowd it will only serve to make things worse.
Also for Black Mages in this thread.
Super Double Flare does the most damage in your rotation and has the least amount of down time as well. (Bard + Int pot Required)
Triple Flare is your next alternative yet it takes longer overall to do. (an additional 4 seconds)
Mini/Baby Ancient Flare spam is way more reliable than the gamble that is Transpose Double flare (Bard + Scholar Required)
Poor Mans Flare is your last thing you do if you don't have any cooldowns up and you need to AoE.
Quad Flare only if the enemy is low.
Quint Flare with a bard help is nice too.
All these are decent alternatives.
Yet doing the transpose double flare method is an exploit on mana regen mechanics and above all the initial Flare is under the Umbral Ice 1 which is gimped AoE damage. So that initial Flare is basically a Fire 2 that grants Astral Fire 3 damage wise and then your next flare is legit Flare damage.
People that suggest the transpose double flare exploit method should not misguide BLM the way they do in making them believe that they are doing more damage because they are not.